GENERAL LABORATORY INSTRUCTIONS 209 



throwing on sand, or moist sawdust, which should be kept in 

 boxes throughout the laboratory. It is an excellent plan to keep 

 a woolen blanket or rug in the laboratory. In case a student's 

 clothing has taken fire he may be wrapped in the blanket and 

 the flames extinguished. Solutions of sodium bicarbonate and of 

 boric acid should also be kept in the laboratory for use if acid 

 or alkali is spattered into the eyes or face. 



In testing for substances present in small amounts, make sure 

 that both the liquid to be tested and the precipitating reagent 

 are perfectly clear, filtering them repeatedly if necessary. If 

 uncertain as to the presence of a precipitate, compare with the 

 original solution. 



As many of the chemical reactions in physiological chemistry 

 are extremely complex, the student need write equations only 

 when they are specifically called for in the notes. 



