216 CHEMICAL MANUEES. 



Bemarks on the Use of Basic Slag. — It is not intended to 

 examine heie the use of basic slag on vegetation ; that examination 

 will find its place better in a special work just published by the 

 author. The remarks made here will therefore be confined to a 

 few points more immediately connected with the study of basic 

 slag. 



Guffroy, an agricultural engineer, having taken in hand re- 

 searches as to what fertilizing action the silica and the manganese 

 had in basic slag, isolated, as well as could be done, the blue crystals, 

 silico-phosphate, and the brown crystals, tetraphosphate, examined 

 above and caused them to be analyzed in Professor Grandeau's 

 laboratory. The following are the results : — 



TABLE LXIII.— ANALYSIS OF BLUE AND BROWN CRYSTALS IN 



BASIC SLAG. 



Trials were made : — 



1. With a basic slag of known composition. 



2. With a basic slag presenting the same composition, and of 

 which the phosphoric acid was furnished by crystals of tetra- 

 phosphate and silico-phosphate of natural basic slag. 



3. With an artificial basic slag, where by using at one time 

 only tetraphosphate, at another time silico-phosphate, there was 



got :— 



(a) A basic slag deprived of silica. 



{h) A basic slag containing little manganese. 



From the comparison of the results obtained it was easy, 

 consequently, to infer the action of the ingredients, manganese 

 and silica. The first researches were made in collaboration by 

 Guffroy, Milon, and Crepeaux. They have been summarized by 

 the National Society of Agriculture.' 



The plants experimented on were buckwheat, wheat, and violet 

 trefoil. Erom this first series of experiments there is deduced the 

 double efficacy of manganese and silica, in basic slag Etoile brand. 

 The second series of experiments, the results of which are not 

 published, were made by Gutfroy and Milon alone, on wheat, 

 buckwheat, and hemp ; at the same time the violet trefoil of the first 



1 " Bullet, de la Soc. National d'Agric, 1905," pp. 479-83 : " On the Feitiliz- 

 ing Action of Certain Accessory Products in Basic Slag ". 



