THE ALUMNI JOURNAL 



137 



- The method. — In the method finally devised, oxidation is made with 

 a weak solution of chromic acid, free from sul])huric acid. The acid 

 is mixed with a small volume of the sample and the liquid at once 

 distilled. The distillate is tested for formaldehyde. 



It was thought that an air condenser which coiild be readily de- 

 tached for cleaning could be employed. The kind, represented in 

 the figure, has served this purpose admirably. In distillation it is held 

 in position by means of a wooden test tube holder secured in a small 

 metal clamp. 



gSSI 



An air condenser. 



The nearly horizontal sections are 16 ins. to 18 ins. long; 



the middle, 14 ins.; tubing ^ in. 



Of the numerous tests for formaldehyde, the modified Hehner's 

 test was selected, and when used as here directed, gave complete 

 satisfaction. Liquids containing other substances should, of course, be 

 distilled direct or after a dilution with water. By using another air 

 condenser, this distillation is performed with expedition, only 5 to 

 15 drops of the distillate being required. 



Reagents needed. — Chrouiic acid solution, in distilled water, con- 

 taining 0.8 per cent, of CrO,, free from sulphuric acid. Albumin 

 solution. — The white of one fresh egg is mixed with 50 c.c. of dis- 

 tilled water, filtered, and preserved with a few drops of chloroform. 

 Less sensitive on long keeping. Aldehyde-free milk answers nearly 

 as well. Ferric chloride solution, containing 0.4 per cent, of ferric 

 chloride corresponding to 0.25 per cent, of iron. Sulphuric acid, pure, 



