"Arnold K. Balls 



199 



That Sulfate was not produced as an intermediate product, in 

 any o£ the tests of the influence of sulfur, is suggested by the fact 

 that none of the ignited precipitates contained detectible quantities 

 of Sulfate; although it is possible that sulfate, after its production, 

 was completely converted to oxid. 



The data pertaining to the foregoing tests are summarized 

 below : 



TABLE I 



Data pertaining to the effects, on the weights of AlPOt precipitates, of ignition 



with sulfur er ammonium phosphate 



A . Standardization value 



B. Constant weight (method of 



Schmidt-Hoagland) 



C. Exposiire for 10 minutes to the 



open air 



D. Constant weight after ignition 



with sulfur (compare with B).. 



E. Constant weight after ignition 



with ammonium phosphate 

 (compare with A) 



F. Constant weight after a second 



ignition with ammonium phos- 

 phate (compare with A) 



92.9 



90.0 



91.3 

 89.9 



93-0 



* Referred to in the text. 



The weight of " aluminium phosphate," obtained by the Schmidt- 

 Hoagland method, varies somewhat according to the temp. of igni- 

 tion. Precipitates, after ignition to constant weight at a low temp. 

 in an electric muffle, lost weight from exposure to a higher temp., 

 and again became constant in weight at the new temp. level. In 

 this way, as many points of constant weight were obtained as there 

 were different *'levels" of temp. involved. It was observ^ed, how- 

 ever, that ignition at even comparatively low temp's failed to give 

 results for phosphate that were equivalent to our standardization 

 values. The losses in weight are illustrated by the data in Table 2. 



The ignited precipitates, obtained by the Schmidt-Hoagland 

 method, are not, as claimed, the normal phosphate; but are either 

 basic phosphate, or normal phosphate contaminated with alumina. 

 Some of these precipitates, ignited to constant weight at white heat 

 in an electric muffle, contained approx. 2 percent less P2O5 than 



