60 EIGHTH REPORT — 1838. 



On the Origin of Petroleum, and on the Natin-e of the Petroleum from 

 Whitehaven. By Prof. JoiiifSTON,'P.Ii.S. 



The author stated that petroleum was obtained in considerable quan- 

 tity from the mass overlying the three several seams of coal Avhich 

 are worked in the neighbourhood of Whitehaven. This petroleum he 

 found to agree in nearly all its characters with that of Rangoon. -In 

 thickness, colour, smell, and especially in the products of distillation 

 alone, and with water, the two varieties agreed ; and as there can be 

 no doubt of the origin of the one variety — that it has been volatilized 

 from the coal into the bed which covers it, and from which it now ex- 

 udes — the author of the paper considered it to be almost certain that 

 the wells of Rangoon must derive their supplies from subjacent beds of 

 coal, and that deposits of combustible matter are to be looked for 

 wherever similar sources of petroleum are met with. 



On Middletonite and some other Mineral Substances of Organic 

 Origin. By Prof. Johnston, F.R.S. 



The name Middletonite is given by the author to a yellow resinous 

 substance found in the body of the coal at the Middleton Collieries, 

 near Leeds, and in other parts of the Yorkshire and the Staffordshire 

 coal fields. It is represented by the formula C.20 H , , O, and is chiefly 

 interesting as being in all probability the resin of certain trees of the 

 carboniferous epoch, more or less altered. 



Of the Resin of Gamboge (^Gambodic Acid) and its Compounds. 

 By Prof. Johnston, F.R.S. 



Prof. Johnston stated that this acid resin is represented approximately 

 by the formula C=, H3 O, and that it forms three classes of salts, repre- 

 sented respectively by 



RO 4- 5 (C5 H3 O) 



RO + 10 (C5 H3 O) 



RO + 15 (C5 H3 O) 



This resin he also stated to be distinguished from all other known 

 resins by dissolving in dilute caustic ammonia, forming a solution 

 which may be diluted with any quantity of vater, and which throws 

 down gambodiates from ammoniacal solutions of magnesia, of the oxides 

 of copper, zinc, siher, manganese, and the other metallic oxides which 

 dissolve in dilute ammonia. No other resin is known to be capable of 

 giving salts from aqueous solutions. 



On a Blue Pigment. By R. Phillips, F.R.S., ^c. 



During the meeting of the Association at Liverpool, Professor Traill 

 exhibited to the chemical section a fine blue pigment prepared by add- 



