8 APPARATUS 



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 dis- 

 tributed 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 difficulties attendant upon the bending of platinum wires and also the possi- 

 bility 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 125 C. 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 glassware 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 center of the tube and with a glass rod push the cotton down the 

 tube about an inch. The cleaning fluid commonly used in laboratories consists of 

 one part each of potassium bichromate and commercial sulphuric acid with ten 

 parts of water. This is an excellent mixture for cleaning old slides, etc. , especially 

 when grease or balsam is to be gotten rid of. It is very corrosive, however. An 

 efficient and less corrosive method for cleansing slides and cover-glasses is to leave 

 them over night in an acetic acid alcohol mixture (two parts of glacial acetic acid 

 to one hundred parts of alcohol). After drying and polishing out of this mixture, 



