Reviews^ and Notices respecting New Books, 53 



1 equivalent barytes 76 1 -^ S'^^^\m loo 

 10 equivalents water 90/ ^^^'^ \ 54*2/ ^""* 



166 



which agrees sufficiently well with my experiment to show 

 that the crystals contain only 10 equivalents of water, instead 

 of 20 as stated by Dr. Dal ton. 



According to Dr. Hope, the crystals of strontia contain 68 

 per cent, of water, and Dr. Dalton concludes from this state- 

 ment that they contain 12 equivalents of it. I prepared some 

 crystals of strontia in the same manner as those of barytes 

 above described; they were dried in a similar mode, and taking 

 the mean of two experiments, which differed but very little, 

 100 parts of the crystals, after saturation with muriatic acid 

 and treatment with carbonate of ammonia, gave 51*57 of car- 

 bonate of strontia; and as 74 of this substance consist of 22 of 

 carbonic acid and 52 base, 51*57 contain 36*24 of strontia, 

 which, deducted from 100, the crystals experimented upon, 

 leave 63*76 as the quantity of water contained in them. The 

 crystals are therefore evidently composed of 



1 equivalent of strontia 52, or 36*621 . . 

 10 equivalents of water 90, or 63*38 J "^ 



142 



and resemble those of barytes with respect to the quantity of 

 water which they contain. 



VIII. Reviews, and Notices 7'especting New Books. 



A Manual of Mineralogy^ comprehending the more recent Discoveries 

 in the Mineral Kingdom. By Robert Allan, Esq., F.R.S.E., 

 M.G.S.L.y 8fc. 1 vol. 8vo, London, 1834. 



MINERALOGY, in its most limited sense, is that branch of Na- 

 tural History which takes cognizance of the forms and exter- 

 nal properties of mineral substances, with a view to their accurate 

 discrimination and to their arrangement into groups or classes. 

 Thus considered, it may perliaps be thought scarcely to aspire to 

 the dignity of a science; but, by its connexions with other branches 

 of human knowledge, it acquires a claim to higher distinction. All 

 the materials of which our globe is composed, however complex in 

 appearance, are resolvable into more simple minerals. In the older 

 rocks, especially, we recognise, by the descriptions of the minera- 

 logist, the proximate materials which compose and characterize those 

 rocks; and hence Mineralogy has been regarded as the alphabet 

 of Geology. The identification of the mass also often depends es- 

 sentially on that of its component minerals. 



