Oe DirectTor’s REPORT OF THE 
DEPARTMENT OF CHEMISTRY. 
A simple casein test— There has long been a need for some 
simple and rapid method by which the amount of casein in milk 
can be determined. Such a method has been finally worked out 
in our chemical department. The method can be readily used 
by any one who is accustomed to the determination of acidity of 
cream at creameries or of whey at cheese factories. It calls for 
simple apparatus only and involves the use of no complicated, 
expensive machinery. The method will find extensive application 
in dairy schools, in all investigations of milk calling for casein 
determinations, at cheese factories, where, in case of abnormal 
milk, as in times of drouth, it is desirable to know the amount 
of casein in order to make cheese to best advantage. This test 
is described in Technical Bulletin 10. 
A chemical study of lime-sulphur washes.— This investigation 
was undertaken to solve some of the difficulties which fruit 
growers have met in making and using lime-sulphur washes. Con- 
ditions of preparation were studied and also the composition of 
commercial washes. The results, as given in Bulletin 319, indi- 
cate that. a concentrated preparation can be best made by using 
125 pounds of sulphur, 60 pounds of lime of best commercial 
quality and water enough to make 50 gallons, the whole to be- 
boiled about 60 minutes. The presence of magnesium oxide in 
lime is a serious detriment, since it causes loss of sulphur by 
producing hydrogen sulphide gas, which is also poisonous and may 
affect uncomfortably persons who are near the boiling mixture: 
for any length of time. The addition of lime to a diluted wash 
causes marked chemical changes which affect seriously the 
insecticidal value of the wash. ‘The commercial preparations 
examined varied considerably in composition. One brand con- 
tained considerable sediment, for which peculiar insecticidal 
value was claimed. This sediment consists largely of sulphite of 
lime which has not been reliably shown to have any marked 
insecticidal properties. 
