i68 Report of the Chemical Department of the 



ARRANGEMENTS FOR COLLECTING GAS EVOLVED BY CHEESE. 



On April i, 1902, each cheese was placed by itself under a 

 bell-jar, each bell-jar being connected with its own apparatus, 

 for the absorption of carbon dioxide. During the entire period 

 of the investigation, the cheeses were kept at a temperature of 

 60° F. (15.5° C.) Through the bell-jars, made tight by mercury 

 joints, were passed daily about 8 liters of air, previously purified 

 by passage through several wash-bottles containing potassium 

 hydroxide. The air from the bell-jar containing the normal 

 cheese was passed through a drying-train of strong sulphuric 

 acid and calcium chloride and then through two Liebig bulbs, in 

 order to absorb any carbon dioxide present. A water-bottle 

 holding 8^ liters was used as an aspirator. The aspirator was 

 started each morning at about 8 o'clock and stopped at 5 ]\ m. 

 Over night, a stop-cock, separating the bell-jar from the wash- 

 bottles containing potassium hydroxide and used for washing 

 the inflowing air, was closed to prevent backward diffusion and 

 consequent loss of carbon dioxide. The bulbs were weighed 

 daily in the early period of the experiment, but only weekly dur- 

 ing the later period. 



In the case of the cheese containing chloroform and kept in 

 an atmosphere of chloroform, the air from the bell-jar was jjassed 

 through sulphuric acid and then tln-ough silver nitrate solution, 

 in order to absorb any hydrochloric acid formed by decompo- 

 sition of chloroform; the air was then passed through three flasks 

 containing decinormal solution of barium hydroxide, to al)sorb 

 the carbon dioxide, and finally through a potassium hydroxide 

 guard. The same precaution against backward diffusion was 

 observed as in the case of the other cheese. Liebig absorption 

 bulbs and direct weighing could not be emplovcd. since the air 

 coming from the bell-jar was constantly laden with va])or of 

 chloroform. To replace the loss of chloroform caused b\- as])ira- 

 tion, fresh j)ortions of chlcjroform were added from time to time 

 through a separatory funnel passing through the top of the bell- 

 jar. A small dish placed on the top of the cheese inside the 

 bell-jar received the chloroform. Once a week the l)arium car- 

 bonate formed was filtered through a weighed Gooch crucible, 

 washed with dilute ammonia, dried and weighed. From the 



