Document x13N79MvL6DX3YnO8BXLa9Zqg

-V . Ju .. IpduitrUI Hygiene Digest < . W- n (. INDUSTRIAL DUSTS &ccmbft 1963 U57 Optimum Conditions tor the Colorimetric Mkrwltlefminitlow of Silicon. j. Turn*. MlkrocMm. Acta No. 3, 512- 523"( 1 9"Vi2 ). (Mikrochiinici AcU SprfngerAVerUg, Moetker* bastei 5. Wien 1, Austria*). :s t yi .i The beet conditions lor the formation of B'lilicomolybdle odd end ite reduction to molybdenum blue, in the presence of phosphate, iron, end some other interfering substance* have been critically investigated to ascertain the moat suitable method for the precise color!* metric microdetermination of silicon in biological material and minerals. The method of King and Stacy (19551 <wae modified by lowering the initial and increaaing the final concentre* tion of sulfuric acid, by securing the same electrolyte concentration in sample and standard and by lengthening the time allowed for reduction of the B-silicomolybdlc acid. These im provements diminish the interfering effect of phosphate and iron and stabilise the molybdenum blue color* The proposed method permits determination of 20*50 micrograms of SiOfc in tbe presence of up to 4*5 mg, of phosphate and 3 mg. of iron, with an accuracy of about 4^ I microgram of SiC^. Alkali fusion was found to be the most suitable way to produec tbe mono meric silicic acid solution necessary for the determination. Details of this method for de termination of silica in tissues and minerals are described and some results Are given. -- APCA Absts. 1158 Hard Metal Disease. A. O. Bach. M. D. Kipling and 3. C. Heather. Brit. J. Ind. Med. J9, 239*252 (Oct. 19621. * i t i *..4 Vv in Great Britain there have been no published reports of respiratory disease occur* ring among workers in the hard metal (tungsten carbide) industry. In this paper the clinical and radiological findings in 6 cases and the pathological findings In one are described. In two cases physiological studies indicate mild alveolar diffusion defects. Histological examination in a fatal case revealed diffuse pulmonary interstitial fibrosis .with marked peribronchial and perivascular fibrosis and bronchial epithelial hyperplasia and metaplasia. Radiological sur* vejrs revealed the sporadic occurrence and low incidence of the disease. The alterations in respiratory mechanics which occurred in Z workers following a day's exposure to dust are described. Airborne dust concentrations are given. The industrial process is outlined and the literature is reviewed. The toxicity of the metals is discussed and the authors* finding* are compared with those reported from Europe and the United States. The authors are of the opinion that the changes which they would describe at hard metal disease are caused by the inhalation of dust at work aed that the component responsible may be cobalt.* Authors' abst. ;!t Protective Clothing as a Factor ir. the Dust Hasard ut Potto.-1. W. A. Flloor and A. Dinsdalc. 5ru. J. im. m irto.iho feitart affec'.ir.'j i\*.' nu*.*sr.tratinrv 5a \i*r breathing none ol pr.rtsry sp-3r\;: -* nv. r t.v>v*n *v: r:.t*.on v-.rr% .* - n `^r.ou* source of dust. At- `eitipts *o v.err.vr.t '* "i*:.' .** * ..*?%tr.*e.v. m* tr.*j v:rr i.r.t \ict.rssfui. so oih^r t .~es of ? ir.*;ekti;at.}C. Tnr/.'jne w%\ fr, ..*.n Mitstandint*.)*/ d*air*blo H propirti#*: ;/ tv.---iec*- *r.d nr v.w.s <,f f o'-wnirwor** defined. Vartory tr*ts <".o*ud that *:i.' tfc:t ..-* .f.'.i'.r.v nf *n 64*1 in *#mthir.g /r.ne rtsst v* uwcairaiior.i ***r^r itr/.f t'r.n t y* * c:otr..na >i r/-* off.aisii/ rftf.j.Msndor. by the Join: Stsr.-smc r. fnnh*. Pv.it; :r.n.*trv. -- Authors' abst. f-V- ?< f II 1 :* i i,