590 REPORT — 1881. 



the oil by alkalies. The taste of the oil and its odour on heating are also useful 

 indications. 



If undoubtedly fluorescent, an oil certainly contains a mixture of some hydro- 

 carbon ; but the converse is not strictly true, as the fluorescence of some varieties 

 of mineral oil can be destroyed by chemical treatment, and in other cases 

 fluorescence is wholly wanting. Still by far the greater number of hydrocarbon 

 oils employed for lubricating purposes are strongly fluorescent, and the remainder 

 usually become so on treatment with an equal measure of strong sulphuric acid. 



The best and most accm-ate method of detecting hydrocarbon oils in, and quan- 

 titatively separating them from, fat oils, is to saponify the sample and then agitate 

 the aqueous solution of the soap with ether. On separating the ethereal layer, and 

 evaporating it at or below a steam heat, the hydrocarbon oil is obtained in a state 

 of purity. The agitation with ether must be repeated several times to eflfect a 

 complete extraction of the hydrocarbon oil from the soap solution. 



The author has proved the accuracy of this process when applied to various 

 mixtures of fat oils with hydrocarbon oils. The results obtained are correct to 

 within about 1 per cent, in aU ordinaiy cases. In cases where extreme accuracy 

 is desired it is necessary to remember that most, if not all, animal and vegetable 

 oils contain traces of matter wholly unacted on by alkalies. In certain cases, as 

 butter and cod-liver oil, this matter consists largely of cholesterin. The proportion 

 of unsaponifiable matter soluble in ether, which is naturally present in fixed oil.* 

 and fats, rarely exceeds 1^ per cent., and is usually much less. Sperm oil, however, 

 constitutes an exception, yielding by the process about 40 per cent, of matter 

 soluble in ether, the nature of which is undergoing further examination. 



The foUowino- table indicates the general behaviour of the constituents of 

 complex fats, oils, and waxes, when the aqueous solution of the saponified sub- 

 stance is shaken with ether : — 



DlSSt)LVED BY THE EtUEU. 



Hydrocarhioi oils, including 



Shale and Petroleum oils 



Rosin oil 



Coal-tar oil 



Paraffin wax and ozokerite 



Vaseline 

 Nhutral resins 

 Vnsapunified fat or oil 

 TJnsaponifiMe matter, as cholesterin 

 Sjjermyl alcohol, from sperm oil 

 Cetyl alcohol, fi-om spermaceti 

 Myricyl alcohol, from bees' wax 



The hydrocarbon oil, having been duly isolated by saponifying the sample and 

 ao-itatino' the solution of the resultant soap with ether, may be fiu-ther examined 

 by observing its density, taste, and smell, behaviour -with acids, &c. 



Rem.\inijjg in the Aqueous Liquid. 



Fatty acids \ i^ eombination 



Resin acids ^j^j^ ^^^ ^j^^^;^^ 



Carbolic and T , 



Cresylic acids/ / 

 Glycerol (glycerine) 



5. On some Tlienomena wliich appear to he of the Nature of Chemico- 

 Magnetic Action. By William Thomson, F.B.8.E. 



Some time ao'o I observed that the colour of a piece of prussian-blue cloth had 

 been dischar'i-ed in the vicinity of a piece of iron which was lying in contact with 

 it and thinking this action to be of the nature of magnetic, I made some experi- 

 ments to learn something respecting it. I laid a piece of glass on a piece of wet 

 •nrussian-blue cloth, and left it there for many weeks ; the eflPect was that the cloth 

 under the "-lass had apparently become rather darker in colour than the original 

 cloth but of this I was not quite certain, whilst the uncovered cloth was slightly 

 bleached. The same effect was produced by laying a sheet of platinum on the wet 

 blue cloth and no blue colour was communicated to the wet blotting-paper on 

 which they lay. These experiments proved that the colour of the cloth was not 

 influenced by capillary action. _ . i., wt. -.v, .^ 



Small pieces of iron were laid on pieces oi the prussian-blue cloth, with the 



