THE LIFE OF KARL WILHELM 8CHEELE xxi 



SCHEELE'S EARLIEST ESSAYS. 



Cream of Tartar. It is a notorious fact that chemical 

 students of the present day are lamentably deficient in the 

 history of chemistry. How many of them are aware that 

 it is to Scheele that we owe the present methods of manu- 

 facturing not only cream of tartar, but also tartaric acid, 

 citric acid, oxalic acid, and all similar organic acids, by decom- 

 posing their lime salts by sulphuric acid ? He who makes two 

 blades of grass grow where only one grew before, is said to be 

 a benefactor to his country. To what extent, therefore, is the 

 world indebted to Scheele for the process for manufacturing 

 these acids alone ? 



1771. Fluor Spar. Scheele, however, was not so 

 fortunate in his examination of fluor spar and fluoric acid. 

 Here his acute faculties of observation failed him : he was in 

 error in regard to actual facts ; in other words, his conclusions 

 were wrong owing to faulty observation. It is a well-known 

 fact, at the present day, that when powdered fluor spar is, so 

 to speak, distilled with sulphuric acid, in a glass retort, the 

 silica of the glass is dissolved by the acid of the fluor, and is 

 carried over, in combination with it, as gaseous hydrofluosilicic 

 acid ; when this gaseous hydrofluosilicic comes in contact 

 with the water, in the receiver, it is partially decomposed and 

 a certain amount of silica is deposited. Now the error or 

 trap into which Scheele fell was in inferring that silica was 

 a decomposition product of fluoric acid itself, and, still strong 

 in his own belief, he tries to show that the same reaction 

 goes on in metallic vessels and therefore independent of glass. 

 Without doubt there was silica present in the fluor spar which 

 he was using, and which he did not take sufficient measures 

 to eliminate. However that may be, his methods of analysis 

 show the master mind of the man who, had his life not been 



