VOL. XXV.] PHILOSOPHICAL TRANSACTIONS. 37 1 



opposite sides are often broader then the other two, and that their ends, when 

 they do not stick to other sugar particles, run into a sharper beetle-like 

 figure. 



In short, we see that the coagulated silver particles, appearing like crystals, 

 are all of them hexangular, and end in two sharp points, and that the rock 

 crystal is almost always of the same figure : and moreover, that saltpetre also 

 coagulates into hexangular figures, with a beetle-like sharp point : but why 

 some coagulate one way, and others another, is a thing inconceivable in my 

 opinion, and which can no ways be accounted for. 



1 likewise put a little gold into aqua regia, and placed the tube, in which the 

 said water and gold was, in warm sand, that as much gold as possible should 

 be dissolved : but I could observe no coagulations in it ; but only in some par- 

 ticles, branching out, the figures of which, by reason of their smallness, I 

 could not perceive. But as to the mixed salts, of which aqua regia is com- 

 posed, viz. saltpetre, vitriol, and sal ammoniac, I saw abundance of their salt 

 particles coagulated ; all which had the figures of exact square diamonds, 

 having two sharp and two obtuse angles ; they were of different magnitudes, 

 some so small that they were hardly to be perceived with a microscope ; most 

 of them as clear as crystal, excepting some very small particles that lay upon 

 them, which had no transparency. 



Fig. 13, shows three of those diamonds, of several sizes ; in which we could 

 perceive a thickness, and the painter has described it accordingly : we saw like- 

 wise some few oblong four-sided figures, with two acute and two obtuse angles, 

 as in fig. 14. I imagined that in the abovementioned figures there was no gold 

 at all, because I scarcely ever discovered any such figures in the aquafortis im- 

 pregnated with silver. There lay also upon, and about, the said diamonds, 

 long crystalline figures, which I conclude were particles of saltpetre. 



An Account of a Book, intitled, A Voyage to the Islands of Madeira, Bar^ 

 hadoes, Nieves, St. Christopher s, and Jamaica ; with the Natural History of 

 the Herbs and Trees, four-footed Beasts, Fishes, Birds, Insects, Reptiles, &c, 

 of the last of those Islands, ^c. &c. By Hans Shane, M. D. F. R. S. 



2 vol.fol. N° 311, p. 2433. 



The author of this work accompanied the duke of Albemarle, as physician, to 

 the West Indies, which gave him an opportunity of making the remarks con- 

 tained in this volume ; which is highly valued for the descriptions and ob- 

 servations in natural history. 



3 B 2 



