EXPERIMENT STATION BULLETINS. 



375 



and picked up in 2% glucose broth tubes and incubated in hydrogen in Novy 

 jars. After a few days plates were made, using litmus glucose agar and in- 

 cubating in Novy jars. From these plates duplicate inoculations were 

 made on slant agar tubes, one tube of each being kept under ordinary con- 

 ditions while the other was kept in hydrogen gas. 



The November and February samples were plated in standard agar only, 

 and after isolation were run in bouillon, gelatin, milk, and the three sugars, 

 dextrose, lactose and saccharose in fermentation tubes. In the February 

 examination only those organisms not typically lactic were isolated. 



Moisture. — About 5 grams of the sample were poured in duplicate into 

 small, flat-bottomed, weighed, porcelain evaporating dishes of 65 mm. 

 diameter, containing short stirring rods. These were weighed, dried at 100- 

 105° C. in the electric drying oven for three hours, weighed, rhied for another 

 hour, and weighed again. The total loss in weight was computed as per- 

 centage of mo'sture. 



Salt and Curd. — To the melted dried butter in the evaporating dishes, 

 ether was added from a wash bottle and stirred well by means of the stirring 

 rods, then decanted through weighed, 9 cm. filters. Several small portions 

 of ether solution were thus decanted through the filters, after which the salt, 

 curd, etc., remaining in the evaporating dishes was washed onto the filters 

 with the aid of the ether wash bottle. The filters were put back into the 

 weighing bottles, dried for a half hour at 100° and weighed for total soUds 

 not fat. 



The dried fi'ters were then put into funnels and thoroughly washed with 

 hot water. The amount of salt in the filtrate was determined by means of 

 standard AgNOg. The difference between this and the total solids not fat 

 was reported as curd. 



Butter Fat. — The difference between the total solids and the total solids 

 not fat constituted the ether extract and was reported as fat. 



The Rancidity {Acidity) tests were made as follows: Samples of about 

 5 grams were accurately weighed in 60 cc. Erienmeyer flasks, melted, 10 

 cc. of ether (1-10% phenolphthalein in ether) added and titrated wdth alco- 

 holic potash. The strength of the alcoholic potash does not remain constant 

 and is determined each time with ^/lo HCl. The results are reported in 

 terms of cc. of ^ /i acid per 100 grams of butter. 



