Notices refpecling New Booh, >?$ 



Many fubftances which have a fine fplendour become tar- 

 nifhed when fc raped : oxygen, by fcratching, as we may fay, 

 the plumbago, produces in it fmall vacuities which difperfe 

 the rays of light, and futfering them no longer to be reflected 

 towards the eye but in a imall quantity : they therefore pro- 

 duce only a weak fenfation, and the body is judged to be tar- 

 nifhed. 



Befides this experiment, in which the black colour gene- 

 rally obferved in the carbonaceous principle feems to us to be 

 owing to its divifion and its texture, we have had occafion to 

 fee the charcoal of turpentine and wax, which are commonly 

 fo black and dull, become brilliant like plumbago when their 

 parts became more compact. 



It is known that Prieftley, that illuftrious obferver, was 

 acquainted with this charcoal of turpentine, and which he 

 pofitively called white charcoal. 



Thus charcoal, whatever be its texture or colour, if it has 

 been heated, is always the fame, contains no hydrogen, and 

 requires for its combufiion the fame quantity of oxygen. The 

 alkaline or earthy matters, which may vary the carbonaceous 

 principle without making any change in it, is not confidered. 



Thefe experiments, indeed, do not prove that the diamond 

 does not make an exception ; but they give us reafon to wifh 

 for a new combuftion of that body, which is too dear to be 

 fubje&ed to this procefs on a large fcale. 



[ To be continued.] 



XVI. Notices re/peeling Neiv Boohs, 



Phihfophical Tranfaclions of the Royal Society of London for 

 the Year 1802. Part i. 



T 



HE prefent part, which is extremely interesting, con- 

 tains as follow: — i. The Croonian Lecture. On the Power 

 of the Eye to adjuft itfelf to different Diftances when de- 

 prived or the Cryftalline Lens. By Everard Home, Efq. 

 F.R.S. — 2. The Bakerian Lecture. On the Theory of Light 

 and Colours. By Thomas Young, M.D. F.R.S. Profeflbr 



of Natural Philofophy in the Royal Inftitution. 3. An 



Analyfis of a mineral Subftance from North America, con- 

 taining a Metal hitherto unknown. By Charles Hatchett, 

 Efq. F.R.S. — 4. A Defcription of the Anatomy of the Or- 

 nithorynchus paradoxus. By Everard Home, Efq. F.R.S.— 

 5. On the Independence of the analytical and geometrical 

 Methods of Investigation 5 and on the Advantages to be de- 

 rived 



