Manchester Memoirs, J^ol. Iv. (1911), No. 10. 



X. The Boric Acids. 



Rv Alfred Holt, M.A, D.Sc. 



Rereived and Read Felniiaiy Jist, igi i. 



An examination of the results of the researches carried 

 out on the anh\-clrous borates of the alkaHes and alkaline 

 earths gives evidence of a number of compounds derived 

 apparently from some more or less hypothetical boric 

 acids in addition to those which are usually accepted as 

 having a definite existence, i.e., the ortho, meta, and pyro 

 varieties. 



Ditte {C. /v., 1873, 77, 785, 893) described compounds 

 of the types 2MO.3BA and 3MO . 2B,0,^, where M 

 represents a metal of the alkaline earths, but Guertler 

 i^Zeit. Anorg. C/ieui., 1904, 40, p. 337) has since shown that 

 these represent eutectic mixtures. This latter author 

 has found evidence for the following compounds : (i) 

 3MO.B.O8, when M is magnesium or barium. (2) 

 2MO.B.O3, when M is any of the alkaline earths. 

 (3) MO.B,0, and M0.2B,0,, when M is calcium, 

 strontium or barium. The present writer has found that 

 in the case of the sodium borates, compounds of the 

 composition NajO . B.O^ and also probably Na,0 . 4B.,0, 

 exist, while the anhydrous stable crystalline form of 

 borax is an eutectic mixture (Proc. Roy. Soc, 1902, 

 74, 285). 



ApnV 20th, igii. 



