348 • ON TWO NEW CRYSTALLINE COMPOUNDS 



100.04 100.00 99.66 100.00 



These analyses tend to prove that crystals formed in alloys between 27.5 and 31.5 

 per cent of zinc correspond very closely in composition to the calculated composition of 

 SbZn.^. 



In its chemical relations SbZn^, unlike SbZnj, is an entirely inactive substance. It 

 does not decompose boiling water except very feebly, and is not attacked by dilute 

 mineral acids. Boiled with strong hydrochloric acid, it is decomposed ; but unless re- 

 duced to a very fine powder, the decomposition is not complete. Strong nitric acid acts 

 upon it as upon SbZna, though the first action is less violent. 



The Variation in Composition of ShZn^ and SbZn.2. 



An abstract of the description of the two compounds of zinc and antimony just 

 given was published about a year since in the American Journal of Science* It was 

 there stated that crystals of SbZuj could be obtained, retaining exactly their crystalline 

 form, and yet containing a very much larger amount of zinc than that which corre- 

 sponds to three equivalents. The important bearing of this fact on many obscure 

 points, both of chemistry and mineralogy, and the circumstance that the large extent 

 of the variation, connected with the fact that the conditions of formation of the crystals 

 were entirely under command, seemed to afford a reasonable prospect of discovering the 

 cause of this remarkable phenomenon, have induced the author to devote the leisure he 

 coiild spare from his profession during the last year to investigating this subject, and 

 it is the especial object of the present memoir to communicate the results of this in- 

 vestigation. The descriptions of SbZus and SbZn2 have been added, in order to make 

 it more complete and more intelligible. 



In the course of this investigation crystallizations have been made or attempted of 

 alloys difiering in composition by one half to five per cent., according to circumstances, 

 from the alloy containing 95 per cent of zinc to that containing 95 per cent of anti- 

 mony ; but only two crystalline forms were observed, that of SbZuj and that of SbZug. 

 Well-defined crystals, like those described under SbZng, were obtained from the alloys 

 between 43 and 60 per cent of zinc, and even in alloys of a higher zinc percentage 

 crystals of the same form were still seen, although they were no longer well defined. 



* Vol. XVIII. p. 229. 



