THE EARTH OR ROCK OILS OF AMERICA. 249 



loss when operating, which I did upon the small scale, was under 



3 per cent. ; but on a manufacturing scale it would likely be much 



more. 



" The oil was fractionally distilled into four equal parts, and the specific 



gravity of each taken ; they were, without giving the odd decimals, as 



follows : — 



1st part 825 c 



\o 



2nd „ 838° 



3rd , 833 



o 



JJ 



4th „ 846° 



" The colour of these distillates vary. No. 1 is a very light sherry ; No. 2 

 is darker • No. 3 is still darker ; and No. 4 is brown. Their boiling points 

 are high. No. 1 is 360° F., and they do not therefore in this respect 

 resemble naphtha. 



" The value in this country of such oils as the one I have operated upon 

 greatly depends upon the quantity of burning oil, or Paraffin oil, as it is 

 commonly, although erroneously called, wbich they may yield upon distil- 

 lation ; the heavier oil, or lubricating oil, being comparatively of little value 

 to the burning oil, and is got rid of with difficulty in the market. Good 

 burning oil should not much, if at all, exceed the specific gravity of 825 p , 

 which is that of the first part of the distillate, and is only one quarter of 

 the bulk of the whole oil. This is a very small yield indeed, and surprised 

 me, as the" crude oil is superior in look, smell, and gravity ; the latter being 

 only 860°, whilst the crude oil from the distillation of the Boghead Coal, 

 the source from which a great portion of the burning oil sold throughout 

 this country is derived, approaches in specific gravity 900°, yet, when recti- 

 fied, the product is two-thirds burning oil. 



" In looking at the specific gravities of the four distillates, it will be 

 observed that the second is of a higher gravity than that of the third, a 

 peculiarity which I have not observed in any of the many distillations 

 which I have hitherto made with oils the production of coals, schists, 

 asphaltes, or peats. Some of the same oil treated with sulphuric acid and 

 soda before distillation gave results much similar, and with the same 

 peculiar difference between the second and third distillates. 



" It is well known to manufacturers of these burning oils that, by re- 

 distilling the heavier oils, a decomposition takes place each time, and some 

 lighter oil is produced ; but the quantity resulting therefrom does not in 

 most cases j ustify the expense of re-distilling, and the loss of the material 

 occasioned by so doing ; so that the above (namely, 25 per cent.) may be 

 taken as the practical yield of burning oil which could be obtained from 

 this sample of oil. 



" Since experimenting with the above specimen, I had another given to 

 me very unlike it. It is dark brown, and has not nearly so much of the 

 green tint about it ; it is much heavier, its gravity being 900°. On standing, 

 it deposits a little water and some yellowish earthy matter. The results 

 from distilling it were less favourable even than from the first. It was 



