WATER IN BUTTER. 221 



passes. At the expiration of an hour the basin is cooled and 

 weighed, and then replaced in the oven for a further half 

 hour ; weighings are made at the expiration of succeeding 

 half hours till the weight ceases to diminish. The lowest 

 weight obtained is taken as that of the dry butter. The differ- 

 ence between this weight and that of the original butter is taken 

 as water. 



3. Four to five grammes of butter are weighed into a wide- 

 mouthed flat-bottomed conical flask, which is placed in a water- 

 oven and shaken every ten minutes for the first half hour, after 

 which it is shaken every half hour. At the expiration of four 

 hours it is cooled, weighed, and returned to the bath for another 

 hour ; if there be any loss, the drying is continued till an hour's 

 drying does not cause any diminution of weight. 



4. From 2 to 2J grammes of well-mixed butter are weighed 

 into a flat-bottomed basin about 2| inches diameter. This is 

 placed in the water-oven till just melted, and 1 to 1J c.c. of 

 strong alcohol are added; the basin is replaced in the water- 

 oven, and weighed after two hours. The loss represents water. 



Of the four methods, the first is the most expeditious, and is 

 nearly as accurate as the others ; the second is the most accurate ; 

 the third is the most convenient if solids not fat and salt are 

 also estimated ; while the fourth is fairly accurate, rapid, and 

 requires no attention. No one of the four methods has, how- 

 ever, any great advantage over the others. 



Gray's Volumetric Method. Ten grammes of butter are 

 weighed into a conical flask of about 70 c.c. capacity, to which is 

 attached a graduated tube fitted with a condensing jacket, and a 

 bulb in which the condensed liquid can collect. Six c.c. of a 

 mixture of 5 parts amyl acetate and 1 part amyl valerate, are 

 added and the flask carefully heated ; the water and a portion 

 of the amyl reagent distil into the bulb, and care must be taken 

 that the steam does not rise higher than half-way up the tube ; 

 if much foaming takes place a little more of the reagent may be 

 added. When crackling ceases, the tube is stoppered, the con- 

 densing water and the jacket removed, and the tube inverted 

 to allow the water and the reagent to flow into the graduated 

 portion ; by swinging the tube sharply all the water is obtained 

 in the tube, and the separation between water and amyl reagent 

 is sharp. 



The tubes are so graduated that the percentage of water is read 

 off direct, when measured at the normal temperature. 



The method is rapid, the boiling taking from five to eight 

 minutes. 



Solids not Fat and Salt. For the estimation of solids not 

 fat and salt the residue from the determination of water is taken 



