270 



On Chemical Tests. 



[Oct. 



III.— On Chemical Tests. — By Lieutenant Braddock. 



To the Editor of the Madras Journal. 



Sir, — Having experienced the want of a book of reference on 

 chemical tests and re-agents, I hive made the following compilation, 

 which may perhaps be found not only generally useful, but, as geologi- 

 cal research seems to be gaining ground in South India, such a compila- 

 tion may be particularly acceptable to many of the subscribers to your 

 Journal, who interest themselves in t such like scientific pursuits and in- 

 vestigations. 



ii. That more regard to chemical testing ought to be paid by writers 

 on the mineralogy of this part of India, seems to be evident from the 

 following observations, for which I am indebted to Captain Campbell, 

 Assistant Surveyor General, who has favoured me with them, and who 

 has had occasion to make extensive experiments in the " qualitative ex- 

 amination" of the minerals of sundry districts under the Madras Presi- 

 dency. 



in. Captain C. says, " Chemistry as applied to the examination of 

 " minerals has been too much neglected in India. — In Europe, where 

 " almost every mineral is known, having been examined by professional 

 " analysts, this is of no consequence ; for a mineralogist can provide 

 " himself with examined specimens, and is able to name any newly 

 (i found mineral, by comparing it with the specimens in his cabinet. 

 " But in India this cannot be done. Gi-eat numbers of our Indian mine- 

 " rals are quite unknown in Europe, hardly any of them have been 

 " analytically examined, and the comparison of them with the speci- 

 tl mens of a cabinet of European minerals is almost useless. In fact 

 " I consider that no person can be a good mineralogist in India, who is 

 *' not also an expert (mineralogical) chemist. 



iv. " The consequence of this neglect of the chemical examination 

 " of minerals has been, that Indian minerals have been most carelessly 

 '* and incorrectly named by various writers in this country : and to such 

 " an extent, that, as the knowledge of geology becomes more attend- 

 " ed to in India, the descriptions of the first writers who have taken 

 " up the subject, will become next to obsolete. Buchanan, Christie, 

 11 Malcolmson, and Benza, have all described the black pillars of 

 u Tippoo's tomb at Seringa patam, as being hornblende, apparently 

 " without one of them testing it even by the blow-pipe. On analysing 

 " the mineral, I find it to be composed of silica, magnesia, alumina, 

 " and iron : and the silica and magnesia being in the largest propor- 

 " tion, it is therefore a silicate of magnesia ; and contains no lime, 

 i( and is quite infusible, while the characteristics of hornblende are 



