1822.] Anali/ses of Books, 143 



Article XV. 



Analyses of Books. 



Philosophical Transactions foi' the Year 1821. Part II. 



{Concluded from p. 63.) 



XVI. Observations on Napthaline, a peculiar Substance resem- 

 hlinga concrete essential Oil, which is apparently produced during 

 the decomposition of Coal Tar by Exposure to a Red Heat. By 

 J.Kidd, MD. Professor of Chemistry, Oxford. (Communicated 

 by W. H. WoUaston, MD. FRS.) 



Dr. Kidd observes that although this substance has been 

 noticed both in the Annals of Philosophy and the Institution- 

 Journal, there has not yet appeared, as far as he has been able 

 to discover, any systematic description of the mode by which it 

 may be obtained, or of its relation to the substance from which 

 it was produced. 



For the mode in which this substance (which Dr. Kidd pro- 

 poses to call naphthaline) is usually obtained, we refer to the 

 journals already mentioned. Dr. Kidd procured it with several 

 other products by passing the vapour of coal tar through an 

 ignited iron tube. 



He first obtained in a condensing vessel an aqueous fluid, hav- 

 ing an ammoniacal odour, and a dark-coloured liquid, resembling 

 tar in appearance ; the properties of both of which are minutely 

 detailed. Some of this dark-coloured liquid was submitted to 

 slow distillation ; the product consisted of two fluids, one of 

 which had the appearance of oil, and the other of water. After 

 these products had passed over, '^ a concrete substance, as white 

 as snow, began to collect in dispersed crystaUine floccuH, in the 

 upper part of the body and neck of the retort, so as, in a short 

 time, almost wholly to obstruct the passage." This was the 

 naphthaline sought for, and its properties are thus given by Dr. 

 Kidd: 



" Properties of the ichite concrete Substance. — Taste, pungent 

 and aromatic. 



" It is particularly characterized by its odour, which is faintly 

 aromatic, and not unlike that of the narcissus and some other 

 fragrant flowers. This odour is readily difl'used through the 

 surrounding atmosphere to the distance of several feet, and 

 obstinately adheres for a long time to any substance to which it 

 has been communicated. 



" When in its purest state, and reduced to powder, it is exceed- 

 ingly smooth, and slightly unctuous to the touch ; is perfectly 

 white, and of a silvery lustre. 



" Specific gravity rather greater than that of water. 



