44 Review of Clea-oeland's Mineralogy, 



common ore of nickel) is ever magnetic, till purified, and 

 whether cobalt is ever magnetic unless impure. 



Professor Cleaveland's remarks on fracture are uncommonly 

 discriminating and instructive, and would lead a learner to a 

 just comprehension of this important point in the characters 

 of minerals. 



The section relating to the chemical characters is concise, 

 and professedly proceeds upon the principle of selection. It 

 might perhaps have been, to some extent, advantageously en- 

 larged ; although, it is true, the author refers us to the par- 

 ticular minerals for individual instances ; still it might have 

 been well to have illustrated the general principles by a few 

 well-chosen instances, e. g. how, by the blowpipe, galena is 

 distinguished from sulphuret of antimony; carbonat of lead 

 from sulphat of barytes, or carbonat of lime ; garnet from tita- 

 nium,; plaster of Paris from soapstone, &c. ; and, among trials 

 in the moist way, how by nitric acid and ammonia, iroii pyrites 

 is distinguished from copper pyrites ; and how, by acids., sulphat 

 of lime is known from carbonat of lime. As the acids are used 

 principally for trials on the effervescence of carbonats, most 

 of which form with sulphuric acid, insoluble compounds, we 

 should doubt whether sulphuric acid is so advantageously em- 

 ployed as the nitric or muriatic, in such cases, on account of 

 the clogging of the effervescence by the thick magena, pro- 

 duced by a recently precipitated and insoluble sulphat. 



According to our experience, the nitric or muriatic acid, 

 diluted with two or three parts of water, is most eligible. 



With respect to the blowpipe : it is a convenience to have a 

 mouth-piece of wood, or ivory, joined to a tube of metal, as 

 Mr. Cleaveland recommends ; and some authors direct to have 

 the tube attached to a hollow ball, for the sake of condensing 

 the moisture of the breath ; but every thing which adds to the 

 expense and complication of the instrument will tend to discou- 

 rage its use ; we have never found any difficulty in performing 

 every important experiment with the common goldsmith's brass 

 blowpipe ; and are confident, that, after the learner has ac- 

 quired the art, or hiack, of propelling a continued stream of 

 air from his mouth, by means of the muscles of the lips and 



