CLEANING GLASSWARE 9 



PRESSURE AND TEMPERATURE TABLE 



5 pounds' pressure, 107. 7C., 226F. 



10 pounds' pressure, 115. 5C., 24oF. 



15 pounds' pressure, 121. 6C., 25oF. 



20 pounds' pressure, i26.6C., 26oF. 



25 pounds' pressure, 130. 5C., 267F. 



30 pounds' pressure, 134. 4C., 274F. 



All such articles as Petri dishes, pipettes, swabs, etc., are wrapped in cheap 

 quality filter-paper, making a fold and turning in the ends as is done in a druggist's 

 package. Old newspapers answer well for this purpose. The sterile swab can be 

 used for many purposes in the laboratory. They are most easily made by taking 

 a piece of copper wire about 8 inches long, flattening one end with a stroke of a 

 hammer, then twisting a small pledget of plain absorbent cotton around the flat- 

 tened end. After wrapping, the swabs are sterilized in bunches. We not only use 

 them for getting throat cultures, but in addition for culturing faeces, pus, or other 

 such material. The pus is obtained with a swab, which material is then distributed 

 in a tube of sterile bouillon or water. With the same swab the surface of an agar 

 plate is successively stroked. This method is almost as satisfactory as the German 

 one of using bent glass rods for this purpose. Everyone has encountered the diffi- 

 culties attendant upon the bending of platinum wires and also the possibility of 

 destroying your organisms by an insufficiently cooled wire. 



CLEANING GLASSWARE 



It is a routine in our laboratory for everything to go through the 

 sterilizer at i25C. before anything else is done. This is a safe rule 

 when dealing with dangerous pathogenic organisms (especially tetanus 

 and anthrax). 



As soon as taken out of the sterilizer the contents are emptied, and the tube or 

 dishes placed in a i % solution of washing soda and boiled. This thoroughly cleans 

 them. As the washing soda slightly raises the boiling-point and also makes the 

 spores more penetrable, it would appear that under ordinary circumstances, it would 

 be sufficient to place all contaminated articles in a dishpan with the soda solution, 

 and boil for at least one hour, not using a preliminary sterilization in the autoclave. 

 The tubes are now cleaned with a test-tube brush, thoroughly rinsed with tap water 

 and placed in a i% solution of hydrochloric acid for a few minutes; then rinsed 

 thoroughly in water and placed in test-tube baskets, mouth downward, and allowed 

 to drain over night. Some laboratory workers boil their test-tubes and other glass- 

 ware in water containing soap or soap powder and, after a thorough rinsing in tap 

 water, drain. Hydrochloric acid should not be used after the soap as it will cause 

 the formation of an unsightly coating difficult to remove. When thoroughly dry 

 they may be plugged and sterilized. To plug a test-tube, pick out a little pledget of 

 plain absorbent cotton about 2 inches in diameter from a roll. Place it over the cen- 

 ter of the tube and with a glass rod push the cotton down the tube about an inch. In 



