OXY-ETHER AND HYDRO-CARBON LIGHTS 101 



carbon ; and Mr. Scott says that this fluid gives the smallest 

 spot of all ; but it requires the jet as well as generator to be 

 heated. 



It is remarkable that Mr. Ives also claims a smaller spot 

 for the same light than when using mixed gases ; but at such 

 trials as I have had any opportunity of witnessing, I was not 

 able to trace this, nor was it the opinion of those present that 

 the light was any better or more silent than that obtained by 

 good operators with mixed gases, as Mr. Scott claims. On 

 the other hand, it is indubitably true th&tfull apertures can 

 be used with this series of oils, and the utmost power of the 

 mixed jet (with such apertures) thus obtained, with only a 

 cylinder of oxygen in the way of gas. As to the claim, how- 

 ever, that still larger apertures can be used with hydro-carbon 

 vapour than with mixed gases, I have never heard of Mr. 

 Scott using more than y^-inch, whilst I have found no diffi- 

 culty (with the jet described in Chapter IV.) in using T ^ 

 nipples with mixed gas, so that this idea is certainly a 

 mistake. It is possible that different operators may obtain 

 rather different results. While, however, there may be 

 occasional convenience in being able to obtain the most 

 powerful light from one bag or cylinder alone, I fear that any 

 apparatus needing heat will be regarded with little favour, 

 and that Mr. Ives's rhigoline or petroleum ether will be the 

 general choice amongst this class of liquids. 



CHAPTER VIII 



LANTERNS AND THEIR MANIPULATION 



55. Single Lanterns. Lanterns for the simple exhibition 

 of single slides are now practically made of one or the other 

 of two patterns. If a petroleum-oil lamp is used, either 

 always, or occasionally, the lantern-body is usually mads 



