168 Tribasic Phosphoric Acid. 



A\ PO U, 0„3 IK). 



1867 L867. CirrolUe i (C. W. III.) 



Al. 0, 2, P0'+2 CaO ::. PO' • 3 BO. 

 L867 L867. Attacolite, (C. W. Bl.) 



Phosphoric acid Beeraa to have been known as a peculiar 

 I before the discovery of phosphorus. A.ngelus Sala, an 

 Italian, who came to Germany and Bettled there, prepared it 

 in L602 from hprns, which he treated with oil of vitriol, using 

 the product as a remedy against the plague of the middle 

 This fact, however, remained unnoticed for over one 

 hundred and fifty years, which is all the more to be wondered 

 is the tendency of the age was to discover new Bubstanci b, 

 and t<> design new modes of preparation. Even after phospho- 

 rus lia<l been discovered in 1669or L670 by Brandt, and, inde- 

 pendently of him, perhaps by Boyle and Kunkel, this wonder- 

 ful sub Bur rounded as it was with invstrrv and to which 

 the imagination attributed miraculous properties, attracted the 

 attention of the Learned to Buch a degree as to divert them for a 

 time entirely from the 6tudy of its compounds. It was onlj at 

 the end of the next century, when the ideas concerning chem- 

 ical composition became clearer, that a number of chemists inter- 

 d themselves in the Btudy of phosphoric acid and of its 

 salts. 



Markgraf (born 1709, died 17 v|, i published in the year 171" 

 a treatise " on tin bearing of phosphorus <>/> metals and half 

 im /<//.-." Bhowing the preparation of phosphoric acid from j>hos- 

 phorus by burning it in atmospheric air, and also by treating 

 it with nitric acid, and he described also many crystallized 

 phosphates. In weighing the produced phosphoric acid he 

 found it in the former case to be 8 to 8^ times heavier than 

 the phosphorus employed for its production, and, inquiring 

 into the cause of this phenomenon, he was very near becom- 

 i oxygon. As it is. we assign to him the 

 the discovery of phosphoric acid in the year 1740. 



