Document 2NvOVmqvOjvp1nZdEBmvjqjgR

Page 2064 1 At that time were there different types of 2 instruments that were available to industrial 3 hygienists to measure dusts? 4 A Well, the basic method that was used -5 there were a couple of devices, but the basic device 6 was called the impinger. 7 Q What is an impinger, and what does it do? 8 A Well, in essence, it is a glass cylinder and 9 looks like a test tube, and you have -- it is like a 10 test tube and then in the middle of this glass 11 cylinder you have a glass pipe that extends down into 12 the median. 13 You fill it with either distilled water or 14 alcohol, and then you suck air through this glass tube 15 in the middle and it bubbles through the liquid, and 16 as it bubbles through the liquid, you collect the 17 particles in the liquid that are impinged into the 18 liquid and.collect. 19 You then go back to the laboratory and you 20 take a small portion of that liquid with a pipe head, 21 shake it up and put it on to a microscope slide that