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PLAINTIFFS EXHIBIT * C73Qa.A\ 1957 Charles S. Pearce, Editor Mary J. Gibb, Atsociait Editor M. Geraldine Smith. Assistant Editor Mary A. Orthoefer. Editorial Assistant Committee on Publications: C. H. Hahner. Chairman: W. Raymond Kerr. J. 0. Eyerhart, and E. P. McNamara Technical Adviser: Margie K. Reser Compiled by The American Ceramic Society, Inc. 4055 North High Street Columbus 14, Ohio strengths, which ore uljtuitteti by using mure caloureuus mixtures and finer grindings. P.L.M. Study ot ring formation in rotary cement kilns. J Sleoten Zement-Kaik-Gips. 9 i9| 397-402 U9cd). --Suggestions are of fered for modifications in design, operation, temperature zones, and fuel to avokl the formation of rings. 19 references. M.Ha. Use of granulated slag cements and of crushed slags in roads and airport runway* in Belgium. Leon Blonoiau. Hev. ma- (r-iaux construction cl irae. publ.. 1956, No. 437, pp. 33-94; N'o. 4KB. pp. 109^-26.--3Iast furnace slag cements gave lower com pressive strength but higher flexural strength than Portland ce ments. Slag as an aggregate is critical in regard to its porosity, density, and adhesion. It is recommended that the slag be compounded according to Parker, be cooled quickly from high temperatures to prevent the formation of unstable dicalcium silicate, be dense, be aged at least two weeks, be cooled to 15 to 2Q*C.. and be homogeneous. B. concludes that slag concrete made with proper care is equal to Portland cement concrete con taining igneous aggregates. 35 figures. 1 reference. P.L.M. X-ray irudy of the ferric phase in Portland cement. Nicola Fratini and Rbnato Turriziani. Ricerca. sci.. 26 [9| 2747- 51 (1956).--The authors describe a chemical method for the separation of the ferric phase of commercial cements, through which its X-ray examination is made possible. The reagent used is an ammonia solution of ammonium citrate (pH -- 11.4; am monium citrate 10% approximately). The results obtained on some commercial cements with different ratios of A!,Ci tn Fe,0 and on a synthetic product of the brownmillerite formula are reported. PATENTS Calcareous matrix body coated with reaction product of an alkali metal borophosphate and a metal silicoflooride. John W. Plauica and Robert E. Parry (Juhns-Manville Cnrp.). U. S. 2,766.140, Oct. 9, 1956.--1. A body comprising staple reinforc ing fibers in a calcareous matrix has a surface hardening and sealing coating thereon, the coating comprising the reaction product of an initial surface impregnant comprising approxi mately 50 to 200 lb. of solids per 1000 sq. ft. of surface treated of an alkali metal borophosphate solution and a coating of approxi mately 5 to 30 lb. of solids per 1000 sq. ft. of surface treated of a solution of a salt selected from the group consisting of zinc and magnesium silicoduorides. D.J.B. Cement manufacture. Frbd O. Db Vanby (Erie Mining Co.). U. S. 2,769,719, Nov 6, 1956.--Portland cement clinker in the form of discrete small spheroids is composed of alkaline earth metal silicates and aluminates. the outer surface layers of the spheroids being composed of essentially unfused particles of alka line earth metal silicates and aluminates and the interiors of the spheroids comprising glassy phase fused alkaline earth metal sili cates and aluminates of essentially the same chemical composi tion as the particles constituting the outer surface layers. D.J.B. Dental impression material. Jambs Crssson (L. D. Caulk Co.). 0. S. 2,769,717, Nov. 6. 1956.-- 1. A composition for tak ing dental impressions consists essentially of an alkali metal alginate, calcium sulfate, and an alkali metal zinc fluoride, the fluoride being adapted to eliminate fixing of the composition while maintaining the shelf life and proper setting time. D.J.B. Formula for cementitious composition. Albert L. Talone. IT. S. 2,769,720, Nov. 6. 1956.--A slow-setting nonshrinking thixotropic water retaining white cement composition capable of use on highly porous surfaces consists, in parts by weight, of 100 Portland cement. 5 to 25 kaolin. 10 to 50 pumice, and 0.62 tn 6.2 parts of a salt selected From the group consisting of sodium chloride and potassium bitartrate. A preferred example is 100 white cement. 10 pumice. 10 kaolin (average particle size 0.5 to 5h), 2.5 salt, and 60 water. Pigments may be added to obtain color variations. D.J.B. Manufacture of plaster of Paris. Walter L. Badger. U. S. 2,767,972, Oct. 23. I95'i --I. The process of calcining gypsum comprises continually moving ground gypsum in the form of a thin layer at a constant rate "l speed through a path defined by surfaces including a hot su.'tace and a moving surface while maintaining the hot surface a: a predetermined heat by conduc tion from substantially saturated vapor at approximately atmos pheric pressure of a condensable liquid having a boiling point in . . excess of 300F. and at the same time regulating the speed of the moving surface to determine the rate of flow of the gypsum over the ho: surface. D J.B. Method and apparatus for burning cement. Eugbn Szincer 0 (Amalgamated Limestone Carp., Ltd.). U. S. 2,770,450, Nov. 13, 1956.-- 1. A method of burning cement in which a granulated mixture of raw cement material and solid fuel is formed into beds on gTaies in a number of independent containers in which -- the burning cycles are staggered, the air flows upward through each bed, and the containers arc continuously or intermittently fed with additional mixtures cf raw material and fuel as the burn ing proceeds, so that the depth of the bed increases as the burning c proceeds from the bottom upward and the combustion zone, during the greater part of the burning, is always covered by a thin layer of fresh raw material and fuel, the burned beds of clinker being successively discharged so that cement is produced -- substantially continuously. D.J.B. Method for the manufacture of calcium silicate type insulation. Willard R. Ssipt (Keasbey & Mattisou Co.). U. S. 2,766,131, Oct. 9. 1956.--1. In the manufacture of calcium silicate insula- ,/ lion having "harsh" reinforcing asbestos fibers incorporated therein, the method of preparing a slurry containing the insula tion-forming ingredients and a quantity of water constituting 3 to 8 times the weight of the total solids present in the slurry com- -- prises intermixing lime and siliceous material with less than half of the total water to be incorporated in the slurry, agitating the mixture to form an intimate dispersion of the lime and siliceous material in the water, thereafter adding additional water and the c harsh asbestos fibers to the dispersion, the amount of the addi tional water being sufficient to bring the total water content to 3 to 8 times the weight of the total solids content, and then further agitating the dispersion to effect uniform dilution thereof with -- the added water and to thoroughly distribute the asbestos fibers therein without appreciably breaking down the length of the fibers. D.J.B. Self-hardening water-glass compositions and proceas of pre- f paring. Karl Dietz (Farbwerke Hoechst A.-C. vorm. Meister Lucius St 3riining). U. S. 2,766,130, Oct. 9. 1956.--Improved acid resistance in the self-curing type of alkali silicate cements is obtained by replacing the fluusilicic acid or other fluorine com- -- pounds used as hardeners with an organic hardener from the group consisting cf esters, amides, and anhydrides cf aliphatic organic acids having equivalent weights of at most about 60. The organic hardener also has less effect on chrome-nickel steels 7 or lead with which the cement might come in contact. The solid constituent comprises an inert filler and 2 to 7% formamide. while the water-glass constituent is selected from the sodium silicates having a ratio of SiOi to NatO less than 2.75 and of SiO, -- to HiO higher than 0.35 and potassium silicates having a ratio of SiOt to K,0 less than 2.25 and of SiOi to Ht0 higher than 0.35. The water-glass solutions have a viscosity of less than 600 centi- poises at 20C. and are used in the amount of 25 to 30 cc./lOO gm. A of the suiid constituent. One example has a composition, in parts by weight of the solid composition, of 90 quartz powder (10 to 25% residue on 100 mesh), 4 clay, 2.5 active silicic acid, and 3.5 glycolide. With 100 gm. of this powder is mixed 30 cc. of a -- .potassium silicate solution in which the ratio of SiOi to K,0 is about 1.64 and that of SiO* to HtO is 0.46. The viscosity of the silicate solution is SO centipoises at 20C. The mixture begins to harden after about 20 min., and setting is completed after 3 1 days at ordinary temperatures. D.J.B. Additional abstract Sect. VII; (patent) Zirconia cement. IV--Enamels and Refractory Coatings for Metals Bright annealing of aheet steel and its use in direct one-coatwhite enameling. Armjn Pstzold and Helmut Bbtzbr. Glas-Email-Keramo-Tcck., 7 [8| 284-87 (1956).--Steel annealed at 780C. for 10 to 15 min. in a protective atmosphere contain ing H, 18. CO 10. CO 4, CH 0.1%, and the remainder N. with H*0 0.15 gm./tn.1, was clean and bright and its surface layer was decarbonized. A one-coat TiO* enamel applied directly to this sheet at 820 to 840C. (2.5 min.) showed good gloss and was free from bubbles and pinholes. Although an annealing tem perature of 1050C. would be too expensive for commercial use. XII--Material! Ceramic industry development and raw material resources of source; (Lnndim). 6 (2| I7t>-.-il liV.-xii - A licscripiimi is given Oregon, Washington, Idaho, and Montana. Hal J. Kelly. ,, of the deposits in the Borr.u Province, Nigeria. 3 references. KaRLE G StRaNDBERC, AND Ja.MES I. MUELLER. U. S. Bur. Y.R E Mines Inform Circ., No 7752, 77 pp. (1956). Free. Pubs. Pellet clay stone from the Southern Coalfield. New South Distrib. Sect . Pittsburgh 13. Pa.--The survey includes annual Wales (Auatralia i. G. Baker Australian J Set. 18 |4I 126- production, some operating costs, and annual power consumption __ 27 (1956)--Pellets constitute about 40% of the rock, and up for the important plants. Id figures. M.J K. China clay for ceramics--its origin, nature, and uses. Richard A. Grbs.n. Pottery Gas.. 81 [954| 1733-35 (1956).--G. discusses to 130/cm ' oi poiished suriace may appear. Chemical analysis shows a kauiimtic composition with some associated titanium bearing mineral matter. X-ray powder photography shows that crystalline structure, chemical composition, grain sice, function j, both pellets and matrix consist of kaalinitc. The pellets are in ceramics, casting, and refractoriness. 6 photos. C.M.C. thought to have been formed by the rolling of small clay balls by Clay minerals from the RBt member of the TrUmric near running water. Preponderance of kauiinite suggests develop GSttingen, Germany. Friedrich Lippnann. J. Sediment. ment under lacustrine conditions in water of low pH. W.O. W. Petrol., 26 (2) 125-39 (1956).--The important clay constituent __ Purification of bentonite by electrophoresia. Nobuhixo is a "swelling chlorite" with a regular mixed layer structure for TaXEUCHI. Bull. Fac. Eng , Hiroshima Untv., 3, 189-94 (1954); which the name "corrensite" was suggested in an earlier paper. Chem. Abslr., 49 |5] 3486c (1955).--A1 is the best metal from Much of the paper is devoted to the specific properties of corren the industrial standpoint for use as the rotating anode in purifv- site. particularly after treatment with several exchangeable e ing bentonite by electrophoresis of a negative sol. The energy- cations. S.A.F. required is 70 to SO watt-hr./kg. of bentonite at a current density Dolomite, principal usea and deposits in France. V. C Harris of about 0.8 amp./dm.'; under these conditions the remaining ' Genie civil, 133, 13-4-36 (1956); abstracted in J. Iron Steel Inst. Fe is about 0.14% compared with the original Fe content of (London), 184 |4] 467 (1956).--C. reviews the composition and _ 3.105%. uses of dolomite and the separation of chalk and magnesite and gives the location and characteristics of the French deposits. Randomly interttradfied kiolin-montmorillomte in acid clay deposits in Japan. Toshio Sudo and Hisato Havashi. Nature, V.R.E. 178 (4542) 1115-16 (1956). 2 figures. 1 reference. V.R.E. Fluorspar and cryolite. John E. Holtzincbr and Louise d Reconnaissance of the ceramic and refractory clays of Western C. Roberts. U. S. But. .Mines Minerals Yearbook (preprint), Austrslia. R. W. Cox. A. C. Frostick, W. G. Garrett, and 1954, Vol. I, 24 pp. (1956). 15e. Govt. Printing Office, Wash W. O. Williamson. Commonwealth (Australia) Set. Ind. Re ington 25, D. C. Gem atone. John D. McLbnecan, Gborgb search Org., Div. Ind. Chem., Tech. Paper, No. 2, 92 pp. (1956).-- SwrTZRR. and Eleanor V. Blanxe.vbakbr. Ibid., 14 pp. -- Sixty-one samples from 43 localities were examined mineralogi- lOp. Graphite. Donald R. Irvinc and Eleanor V. Blanken- cally and by physical tests. Testing methods and the ceramic bakbr. Ibid., 11 pp. 101. Jewel bearings. Hbnry P. assessment of results are discussed. Many clay deposits re Chandler and Eleanor V. Blanicenbaker. Ibid., 4 pp. 5i. mained in place on rocks from which they had been derived by 1 figure. Syenite snd related minerals. Brooks L. Gunsallcs e intensive weathering. Some of these contained excessive amounts and Frances P. Uswald. Ibid., 6 pp. 5d. Perlite. Olives of grit, iron and titanium compounds, or soluble salts. Lacus S. North and Anntb L. Marks. Ibid.. 7 pp. 10c. Pumice trine clays were also represented. Clays were classified as kao and pumicite. Oliver S. North and Annie L. Marks. Ibid., lins and semiball, ball, and bentonitic clays. Some are of pos- 9 pp. 10c. 1 figure. Talc, soapstone, end pyrophyllite. -- sible use in earthenware, china and related bodies, in firebrick, Donald R. Irving and Frances P. Oswald. Ibid., 12 pp. and as bond or coating clays. 31 references. W.O.W. 10c. I figure. Vermiculite. Oliver S. North and Nan C. Smaitte--mineral apecimecs No. 37. Anon. Mine or Jensen. Ibid.. 10 pp. lOi. M.J.K. Quarry Eng., 22 [10| 412-13 (1956).--The synonyms, nomen- Fuaed-qaam fibers--a surrey of properties, appliesdons, and / clature, varieties, composition, crystallography, physical proper production methods. Nancy J. Ticks. Sad. 3ur. Standards ties, tests and diagnosis, occurrence, and uses of smaltite (CaAsi) (U. S.) Cir;.. No. 569, 26 pp. (1953). 25e. Govt. Printing are presented in orthodox textbook style. Cobalt compounds Office. Washington 25. D C.--T. presents a summary, including are used in ceramics, especially for making blue giass. enamel. a bibliography, of a literature survey on the properties and the -- pottery, etc. 3 figures. V.R.E. uses of fused-silkra doers. Such fibers, frequently called quartz Sol~.c Australian silica deposits aa potential sources of silica fibers, have had wide application in precision measuring instru brick. R. R. Huchan. Cay Products j. Australia. 23 !8) 3-9 ments despite the fact that the factors which affect their behavior (1956).--Chemical and physical data are given for samples of are not fuily known. Much of the information on their pro 3 silica, mostly from the States ol Victoria. New South Wales, ar.d duction methods and properties is widely scattered throughout South Australia. The rocks included sedimentary quartzites, the technical literature. The subjects discussed include applica silicified limestone, material silicified beneath basalt flows, and tions. methods and apparatus, mechanical properties, and other silcretes. The silcretes resemble those of South Africa and properties, viz., structure, chemical durability, permeability, " were found in the Oodnadatta region of South Australia. Satis sorption, hardness, density, devitrification, thermal expansion, factory' experimental brick were made from several quartzites. and viscosity. 325 references. W.O.W. Lead ia the Ceramic Industries. Prepared by the Ceramic Surface adhesion and elastic properties of mica. George L. Technical Committee or the Lead Industries Assoc Pub ** Gaines, Jr., and Davtd Tabor. Nature, 178 [4545] 1304-1305 lished by Lead Industries Assoc.. New York 17. 1956. 40 pp. (1956). 1 figure. 4 references. V.R.E. "Macrocrystalline" carbon. D. E. Palin. Nature. 178 Titaninm nitride--its preparation and "hard-metal" proper [4537] 809-10 (1956).--?. describes the interlayer spacings, ties. I. C. Kraitzer and I. E. Nhwnham. Australian J. Appi. properties, etc. 1 figure. 3 references. V.R.E. Set., 7 |3| 215-23 (1956).--TiN was made by passing NHi and Mineral resources of the San Carlas Indian Reaerotioa, TiCL through a stainless steel tube at 600*C. Iron contamina Aril. C. S. Bromtibld and A. F. Shridb. if. S. Geoi. Survey tion of the nitride during preparation and subsequent bail milling Bull., No. 1027-Jf, pp. 613-91 (1956). 51.25. Govt. Printing assisted the sintering of compacts. Attempts to sinter pure Office, Washington 25, D. C.--The San Carlos Indian Reserva nitride prepared by another method failed below 2000C. Addi tion covers about 2800 sq. miles in east-central Arizona. As tion of Fe permitted sintering below 2000C. Strength and bestos, the most important mineral resource, is found in the hardness decreased but subsequently rose to a maximum at 11% Mescal limestone of pre-Cambrian age near intrusive diabase. Fe. Addition of Mo to nitride containing Fe caused little change Small amounts of building stone, peridot, and guano have been in sintering temperature or strength but greatly increased hard mined commercially. Deposits of gypsum and impure diato- ness to a maximum at 10% Mo. Compacts with 2% Mn had maceous earth of unlcnown value occur in late Tertiary lake beds. physical properties similar to those of compacts with 10% Mo. A low but anomalous degree of radioactivity is prevalent in the Metallographic descriptions are given. Methods for analyzing Dripping Spring quartzite of late pre-Cambrian age. Minor de titanium nitride with metallic additions are discussed. 2 figures. posits of copper and iron minerals are known. 10 figures. 13 references. W.O.W. M.J.K. Veinlets and similar formations in bauxites. S. I. Bhnsslav- Nigerian diatomite. E. R. Vaklzy, J. W. du Prbsz. E. A. SKlf. Doklady Akad. Nauk S.S.S.R., 97, 729-32 (1954); Chem. Parkin, and Enid C. Scott. Colonial Geoi. and Mineral Re Abstr., 49 |3| 1497g (1955).--In gibbsite and boehmite-diaspore 1957 V--Glass -'31 using a through-fiuine technique for their preparation. The distributions obtained confirmed the earlier work with the ex ception that cyclic phosphates were found in solutions of glasses having or approaching the metaphosphate composition despite g prolonged heating of the glasses in the molten condition. The earlier observation was that prolonged heating eliminated the cyclic phosphates. As before, no orthophosphate was found, as predicted by Van Wazer, and neither the Poisson nor the "random reorganization" distributions fitted the data for both high and low average chain lengths. Although some sort of rearrangement is occurring in the melt, it may not be a compleiel/ random process; a rapid change of chemical properties with chain length of the short polymers may have to be taken into account. This was confirmed by similar studies of potassium and lithium phos phate glasses, whose distributions were found to be different enough to demonstrate a cation effect. Consequently, more __ than stoichiometry is involved. 8 figures. 19 references. Diamond glass wheel working machinery. M. H. Hawkins. Glass, 34 [51 215-17(1957). 5figures. V.R.E. Slecoon micro*cope investigation* on opal glas* break for- c face*. Funk Ksrkhop, Robert Sesligbr. and Walter Westfhal. GlasUch. Ber., 28 [7] 262-64 (1955).--Electron micrographs were made of tungstic oxide shadowed collodion replicas from opposite surfaces of a break in opaque glass. The -- tiny crystals embedded in the amorphous glass were usually irregular lumps; only seldom were cubic crystals indicated. They were thought to be chiefly NaF in view of the composition of the glass, which is not. however, given. The pattern of the d crystals in the glass permitted matching pictures of the opposite break surfaces exactly. There was no evidence of plastic flow of glass under the stresses involved in the breaking process. There were tall spikes on most of the crystals projecting from the glass -- surface, evidently due to sticking and flow of the collodian membrane during the stripping operation. Behind each pro jecting crvstal a tiny flag U.5 to 1.0 long appeared in the glass surface. The directions of these flags indicated the direction c in which the crack traveled when the glass broke with an average error of 5 to 7". They were due to the break traveling at different levels around the fluoride crystals, thus forming tiny terraces or steps. The number of crystals per square millimeter -- of surface passed through a minimum of 14 X 104 at a distance of 2 mm. from the fire-polished surface of the glass. From this point the number increased toward both surfaces, reaching 19 X lOVmm.1 at a distance of 0.5 mm. from the fire-polished surface , and 24 X 104/mra.* at a distance of 1.5 mm. from the opposite, mat. surface. The crystals were finer and more numerous in the vicinity of the mat surface, where the glass was cooled most rapidly during the pressing process, than in the vicinity of the__ fire-polished surface. Class thickness was 8.5 mm., and Che crystals ranged from 0.1 to l.Op in diameter. 4 figures, 8 refer ences. C.H.G. Gl*** as fertilizer. Karl T. Nestle. GlasUch. Ber , 28 g [51 194-97 (1955).--Developments in the U. S. and Germany are reviewed. The base glass, which must not be too soluble (<7%), is obtained by replacing a substantial part of the silica of ordinary glass batches with phosphoric oxide, e.g., SiOi 38.8. __ P,Oi 20.9. FejO, 5. MnOi 4. CaO 822. MgO 8.2. K.O 9.2, and NaiO 9.2%. Trace elements may be added in various propor tions according to soil and crop requirements. 20 references. C.H.G. h Glass in the hands of our ancestors. W. E. S. Turner. GlasUch. Ber., 28 (7| 255-59(1955).--Historical. 5 references. C.H.G. Glass polishing: I, Optical polish. Ernst BrUchs and -- Helmut Poppa. Glastech. Ber., 28 [8| 232--42 (1955).--Electron micrographs were made of metal-shadowed replicas from 12 samples of optical glass disks taken at various stages of polishing with Uni-Oxide, a 70% ZrOt powder with a maximum in the, i particle size distribution at about 0.25*t- The presence of nneven smeared areas in the highest lying zones of the initial ample showed that the polishing process had begun during the last stages of fine grinding. In the first minute of polishing -- this process of smoothing the high spots was greatly extended. It appeared to be due to plastic flow of che glass under pressures of about 50.000 kg./cm.1. Such flow without cracking under sharp pointed silicon carbide grains with a moderate load was j shown by an electron micrograph which also showed the cracking and tearing that occurred when the load was increased and the polishing action went over to grinding. The erasure of one trace by piastic ffow when' another trace crossed it was also demon strated. 'This polishing process appeared In occur only un the high spots, and no filling in of craters left by grinding was ob served as a result of either the plastic flow of the glass or the adherence of displaced material in the low spots. As the polish ing progressed, the smooth spots enlarged and finally joined, leaving rough areas where the suriace was originally depressed. No polishing action takes place at the bottom of such low spots since the polishing grams must be supported directly by the pitch of the polishing cap to exert the pressure necessary for plastic flow of the glass. The ratio between the measured pressure during polishing of 150 gm./cm 1 and the pressure necessary for plastic flow, 5 X 10: gm./cm >. indicates that the active surface if polishing medium actually in cnntact with the glass amounts to only 3 X 10~* cm.'/cm.1 of lap surface. From the average size of the polishing grains, the number of grains in a 1-grain layer is calculated to be 16 X lO'/mm.1. The ratio of surface uf the grains in actual contact with the glass to projected area of the grains indicates that the pressure traces or scratches made by the polishing grains in the glass surface arc about 1 mu. deep With the normal rate of polishing, successive grains pass over the glass at intervals of 111*4 sec., which may be a short enough time so that the surface of the glass remains in a plastic state con tinuously. "Table" cracks are found marking off elevated or depressed areas 3 few microns in diameter. These are ascribed to the action of abrasive particles under high pressure which pro duce cylindrical cracks running perpendicularly into the glass. The initial stages oi polishing progress rapidly, but the final elimination of low rough regions requires a relatively long time because glass must be wiped from the smooth high surface until the level is reduced to that of the valley bottoms. 22 figures. 13 references. Cf. Ceram. Abslr.. 1956, Sept., p. 186/. C.H.G. Identification of inorganic fibers. W. Bobsth and U. M0u.br. Faserforsch. a. TextilUch.. 7, 497-504 (1956); abstracted in J. Appl. Chem. (London). 7 |5| i--417 (1957).--A rapid microchemi- cal method for identifying slag fiber (I). mineral fiber (II). ceramic fiber (HI), glass fiber (IV). quartz fiber (V), and asbestos fiber (VI) comprises treating the fiber sample successively with the following reagents which give the results indicated; (1) 2% HtSO. I dissolves with the formation of CaSO crystals; (2) 37% H1SO4, II dissolves with formation of CaSO. crystals; (3) a 1:1 mixture of 37% HtSO. and 10% HF. both IH and IV dissolve. Ill without residue and IV with formation of crystals or acomy besiaue; (4) a 4:1 mixture of 20% HF and 5% aqueous K ferrocyanide. both V and VI are undissolved but VI tarns blue or green according to the asbestos type and V is uncolorec. Tests for distinguishing between the members cf the individual fiber classes are as follows: (a) with a 1:3.5 mixture of 15% HC1 and 5% aqueous K ferrocyanide. slag and mineral wool give different color changes; (4) with 17% HtSO and 10% HF. Silan dissolves with crystal formation and basalt without residue; (c) with a 1:1 mixture of 37% HSO and 10% HF. various types of glasses give different crystal types in different amounts; and (d) with 40% HF (and other reagents), various types of as bestos give characteristic color changes or crystal forms. 12 references. V.R.E. Instruments for the determination of the physical properties of glasses. H. Schulz. Glas-Email-Kcramo-Tech., 8 |5) 157-60 (1957).--A brief review is given of the simpler forms of apparatus for determining refractive index and dispersion for production quality control. Approximate values are obtained by measuring the shift of the image viewed through a slab of the glass, and more accurate measurements are made with a refractumcter or by goniometric observations on a beam passing through a prism. Apart from the general refractive index of the sample, it is essential to be able to detect small variations from point to point which may be caused by inhoniogeneities such as cords. A relatively simple observation of the strain pattern in polarized light can detect a variation of one part in a million. 1 figure. J.A.S. Kinetics of slow fractures in glass. W. C. Lbvbncood and W. H. Johnston. J. Chem. Phys., 26 [51 1184-85 (1957).-- Fractures in plate glass originating at a cutter mark and pro gressing slowly parallel to the surface were observed under controlled conditions. The rates of spread of such fractures, immediately after the glass is cut and for several hours afterward, were determined by viewing microscopically the movement of interference fringes produced in monochromatic light. ESects of external atmosphere and of various gases introduced during melting are described. A theory of the kinetics of slow fracture rates is offered, which relates the fracture spreading rate to the