154 



below 80 C.), the cylinder being closed with a moistened cork stopper and the con- 

 tents shaken several times after the addition of each. The cylinder is then left 

 standing for six hours or more. The clear fat solution is next pipetted off into a small 

 weighed flask by means of a siphon drawn to a fine point (fig. 6, loc. cit.), which is 

 lowered into the fat solution to within 0.5 cm of the turbid bottom layer. After 

 evaporating the ether solution in a hood, the flasks are dried in a steam oven for two 

 or three hours and weighed. This method is applicable to new milk, skim milk, 

 buttermilk, whey, cream, cheese, condensed milk, and milk powder, but has been 

 found of special value for determining fat in skim milk, buttermilk, cheese, and con- 

 densed milk. T In the case of products high in fat, a^econd treatment with 10 cc each 

 of ether and petroleum ether is advisable in order to recover the last trace of fat. 



Chemists are requested to make at least two determinations by the methods given. 

 On account of the quite large variations in the results reported by the chemists last year, 

 the referee is very anxious to determine whether the differences are due to the inac- 

 curacy of the methods or to the manner ia which they are handled by different men. 

 Everyone who has had much experience in making sugar determinations realizes 

 how easy it is to get quite large variations in results by varying the method slightly. 



If methods materially different from those given above are being used by anyone 

 taking part in the work for the determination of sugars or fat in condensed milks, the 

 referee will be glad to have results by such methods reported. 



J. M. BARTLETT, 



Referee, 

 L. G. MICHAELS, 



Associate referee. 



Eleven different chemists reported on the samples sent them and their results are 

 given in the following table, together with some obtained at the Maine station: 



Cooperative work on samples of sweetened condensed milk (percentage results). 



a Omitted from average. 



b Dried on sand and extracted once. 



Extracted twice. 



