516 Royal Society : — 



colour of alizarine. Some time must however elapse before the great 

 number of new bodies can be fully studied. 



Hydrocarbons not acted upon by Sulphuric and Nitric Acids, 



The hydrocarbons which resist the action of monohydrated sul- 

 phuric and nitric acids form, as has been before stated, by far the 

 larger portion of the distillates obtained from Burmese naphtha. 

 When purified by washing from adhering acid, by fractional distilla- 

 tion, and finally by rectification in a current of dry hydrogen gas over 

 the liquid alloy of potassium and sodium, they are obtained almost 

 inodorous and perfectly colourless. Thus purified, they are very 

 fluid, aud retain their fluidity even in the intense cold produced by 

 a mixture of solid carbonic acid aud ether. No absolute fixity of 

 boiling-poiut could be obtained in any of the products ; nevertheless 

 a much greater constancy in this respect was observed than with the 

 hydrocarbons before treatment with strong acids. The lowest boiling- 

 point obtained was 50° C. (122° F.) ; the highest, being far beyond 

 the range of the mercurial thermometer, was not ascertained. The 

 specific heat of the vapour of all this series of hydrocarbons was 

 ascertained to be very small, a fact which we believe accounts iu 

 some measure for the difficulties we experienced in the fractional 

 distillations. For the purpose of analysis, we have contented ourselves 

 with selecting such products as boiled within the saine 5° C. (9° F.) 

 of the thermometric scale. All the analyses tend to prove that the 

 ratio of carbon to hj'drogen increases slowly with an increase in the 

 boiling-point, and to negative the not improbable assumption of the 

 carbon aud hydrogen being combined iu equal equivalents. The 

 general formula C^ !!„+, agrees best with our results, and indicates a 

 probability of the Burmese naphtha containing several radicals or 

 their hydrides. 



Our endeavours to obtain definite substitution-compounds by 

 means of bromine and chlorine have been attended with only partial 

 success. Chlorine gas acts slowly in the dark, but more quickly 

 with the aid of difl'used daylight ; pentachloride of antimony, on the 

 other hand, acts with so much violence that explosions frequently 

 ensue. 



Bromine appears to separate the hydrocarbons into two distinct 

 bodies, a circumstance which throws some doubt upon their simple 

 constitution. Hydrated sulphuric acid saturated with the anhydrous 

 acid likewise produces a separation of the hydrocarbons, absorbing 

 one portion and leaving the other unacted upon ; anhydrous sulphuric 

 acid, on the other hand, in some cases completely absorbs the whole, 

 sometimes with evolution of sulphurous acid. The copulated sulpho- 

 acids which are produced in these cases will probably enable us to 

 clear up the enigma of the composition of the hydrocarbons ; we 

 think it better therefore not to lay much stress upon the Radical or 

 Hydride hypotheses until further experiment has thrown more light 

 upon the subject. Nevertheless we may state, that by operating 

 upon a fluid boiling between 90° and 100° C. (194°-2r2° F.) with 

 chlorine for some months, we at last obtained a cessation of all 



