2 Holt, TJie Boric Acids. • 



Very little attention seems to have been paid during 

 recent years to the boric acids, and most of our knowledge 

 of these compounds is due to the researches of Ebelmen 

 and Bouquet {Ann. C/iiin. Phys., 1846,3, 17,63), Schaff- 

 gotsch {Pogg. Annal, 1859, 107, 430), and Merz(/. Prakt. 

 Cheni., 1866, 99, 179). Ebelmen and Bouquet, by 

 examining the rate of dehydration of orthoboric acid, 

 concluded that at least two other acids existed, and in 

 support of this view described organic derivatives analo- 

 gous to borax, and an orthoborate. 



Schaffgotsch observed that when orthoboric acid is 

 heated on a water-bath for some time, two-thirds of the 

 water it contains is removed, leaving a vitreous substance 

 which could only be deh)'d rated completely by heating 

 to a very high temperature. 



Merz confirmed the observations of Schaffgotsch, but 

 considered that several acids containing less than a third 

 of the water of orthoboric acid existed. He also noticed 

 that orthoboric acid was volatile to some extent in the 

 water vapour given off on heating it. 



The molecular weights of neither the anhydrous 

 borates nor meta and pyro boric acids are known, and 

 consequently their formulas are only empirical, but the 

 constitution of the ortho acid is well established since it 

 forms a volatile triethyl derivative. 



The experiments described in this paper were carried 

 out to see whether the meta and pyro acids were really 

 definite compounds or mixtures, and whether any other 

 acids existed. 



In the first series of experiments a weighed amount 

 of orthoboric acid was heated in a platinum dish at a 

 constant temperature and the loss in weight determined 

 from time to time. 



