W. Skey. — On the Mineral Oils of Neiv Zealand. 2/53 



a rule, the more carbonaceous the oil, the greater its specific gravity and the 

 higher its volatilizing point. 



Petroleums are, as a rule, mixtures of hydrocarbon oils differing very 

 greatly in density and consequently in volatilizing points, charged more or less 

 with paraffin — a hydrocarbon oil solid at common temperatures ; and also with 

 bituminous or pitch matters, to which last they owe their colour ; and it has 

 been found that with most or all our petroleums their lightest and their 

 heaviest oils are unfit for the highest use we can put them to — that is, for 

 illuminating purposes ; consequently they are separated from the rest by 

 fractional distillation, and the oils of intermediate density thus obtained only 

 require treatment with sulphuric acid and an alkali successively, and to be 

 finally re-distilled, to fit them for their destined use, the acid being iised to 

 clear the impurities contained in the oil, and so to convert them into such a 

 form that they can be removed from the oil by water. 



It will be observed how very simple the process of refining these oils is, 

 all that is required being steadiness in the distillation, the use of certain 

 chemicals in quantities proportionate to the amount and nature of the 

 impurities present in the oil operated upon, and the proper division of the 

 distillate. I may state that these oils are far easier to purify than those 

 obtained by the destructive distillation of any kind of carbonaceous substance. 



Having thus stated briefly the nature of these oils, and the means 

 necessary to fit them for illuminating purposes, I will now proceed with 

 the subject of this paper, in the hope that, by the aid of the foregoing 

 remarks, I may be understood throughout, even by those who may have 

 been hitherto unacquainted with the manufacture in question. 



The oils I have had the opportunity of examining vip to this time are of 

 three distinct kinds, and from as many distinct localities : 



1. The Sugar Loaves, in Taranaki Province. 



2. Poverty Bay, on the east coast of the Province of Auckland. 



3. Manutahi — Waiapu, East Cape. 



1. The first, that from the Sugar Loaves, is a very remarkable oil, its specific 

 gravity being no less that "960 to '964 at 60° Pah., water at 1. The heaviest 

 petroleum mentioned by Gesner, -927, has a specific gravity of about -930. 



All the various samples which have been submitted have the same physical 

 characters, having a dirty green colour by reflected light and being opaque, 

 unless examined in thin films, when it has a deep red colour by transmitted 

 light. 



At 60° Fah. it is quite liquid, and though at lower temperatures it has 

 considerable consistency, yet when reduced to 5° Pah. it does not become 

 solid. 



It has a mawkish but not unpleasant odour, being very diflerent in this 



