Table III. Gypsum or Land Plaster. 



Howard's Agricultural Talc 

 Registered by L. A. Howard Talc Co., Inc., Proctorsville, Vermont. 



This material was analyzed at this laboratory in considerable detail late in 

 1935. The results of this analysis are given herewith as it furnishes a better 

 picture of the actual composition and behavior of the material than does a 

 later analj^sis of a sample secured by our inspector in 1936 which was simply 

 analyzed for its content of acid soluble calcium and magnesium oxides in order to 

 check the acid soluble magnesium oxide which was guaranteed under registration. 



By fusion: 



Magnesium oxide 



Calcium oxide 



Iron and aluminum oxides .... 

 Insoluble sihceous matei'ial 



By dilute 1-1 hydrochloric acid: 



Magnesium oxide 



Calcium oxide 



Iron and aluminum oxides .... 



Insoluble matter 



Volatile matter (largely carbon dioxide) 



Analysis in 1935 

 Per Cent. 



32.64 



1.24 



9.12 

 41.05 



13.87 



1.19 



5.21 



64.72 



15.02 



In order to test the solubility of the magnesium contained in the talc, various 

 solvents were used and the recovery of magnesium oxide is given as follows: 



H Gi-am boiled with 150 cc. di.stilled water made 

 slightly acid with hydrochloric acid + 15 cc. of satu- 

 rated solution of ammonium oxalate 



Magnesium Oxide 

 Recovered 

 Per Cent. 



5.58 



1 Gram boiled 5 minutes with 100 cc. of 1'7 hydro- 

 chloric acid 8.87 



1 Gram boilcid with 100 cc. of 1% hydrochloiic acid 



+ 5 grams of ammonium chloride 13.13 



1 Gram boiled with 200 cc. of 2% citric acid solution . 5.52 



