32 INSECTICIDES AND FUNGICIDES. 



COPPER SULPHATE. 



[Serial No. 20369.] 



Composition of Copper Sulphate. 



Per cent. 



Sand : 0. 05 



Copper oxid 31. 48 



Sulphur trioxid 32. 13 



Water of crystallization and hygroscopic 36. 00 



99.66 

 This compound is an excellent sample of CuSO 4 5H 2 O. 



GRAPE DUST. a 



[Serial No. 19690.] 



Composition of Grape Dust. 



Per cent. 



Sand 1. 64 



Sulphur 58. 82 



Copper oxid 90 



Calcium oxid 11. 93 



Sulphur trioxid 17. 04 



Water to form CaSO 4 2H 2 O 7. 67 



Tobacco (by difference) 2. 00 



100. 00 



This substance contains sulphur and copper oxid probably in the 

 form of copper sulphate, which is of value in treating surface mildew 

 on the vine. The amount of tobacco is too small to be of any value. 

 The gypsum adds weight, and serves as an agent to mitigate the action 

 of the sulphur and copper sulphate. 



SOAPS. 



In making an analysis of this class of compounds, the following 

 determinations were made: Moisture, total fatty matter, total alkali, 

 free alkali, and in certain cases calcium oxid, neutral fat + unsaponifi- 

 able matter, and resin. The methods 6 follow: 



METHODS OF ANALYSIS AND DISCUSSION. 



Moisture. Weigh a 100 cc beaker containing about one-half inch of 

 recently ignited sand and a small glass rod. Add about 5 grams of 

 the sample, and weigh again. Dissolve the soap by means of 25 or 



See correspondence with manufacturers, page 60. 



* Most of the methods are from "Oils, Fats, and Waxes," by Benedikt and Lewko- 

 witsch, with slight modifications. 



