CHEMICAL SCIENCE. 309 



bones almost to powder ; then to treat them with this agent, which almost 

 instantly dissolves all the grease contained in them ; and from this it may 

 be separated by distillation, which is greatly facilitated by the low tempera- 

 ture at which this fluid boils, and the ease with which it may be condensed. 

 The quantity of grease thus obtained is 10 or 12 per cent., and it is superior 

 to that procured by boiling. 



He adds, that the same agent may be applied to the extraction of oils from 

 oleaginous seeds and of the grease from wool. In the latter case the grease 

 extracted becomes a useful product ; it is a butyraceous substance, adapted 

 for the manufacture of some kinds of soap. 



ON SOME NEW METHODS OF TREATING LINSEED OIL. 



The following is an abstract of a paper recently read before the Society of 



Arts, London, by Mr. C. Binks : 



Linseed oil appears in four different forms : 1st, the oil in its natural 

 state, called raw oil ; 2ndly, this raw oil refined, or from which has been sepa- 

 rated its mucilage and coloring matter ; Srdly, the raw oil boiled, that is, 

 made or intended to be made more drying than the original oil ; and 4thly, 

 the raw oil put into a variety of conditions as to thickness, color, etc. The 

 strongest oil used by the artist's color-maker the writer found to consist 

 chemically of a solution, in any excess of oil, of the oleate of lead, which 

 had obviously been made by heating raw oil along with litharge and water, 

 and afterwards expelling, by heat, the excess of water used. This kind dried, 

 per se, in fifteen hours. 



The refined oil, in paint-making, is employed chiefly as the vehicle in 

 which to grind white pigments. The raw oil is used to thin and prepare for 

 use the finer kinds of paints, from which boiled oil is excluded by its dark 

 color and after-effects. The raw oil is, of itself, a very slow drier. The re- 

 fined is still more imperfect in this respect ; and hence, to quicken the work 

 of the operative painter, arises the necessity for using, along with these two, 

 spirits of turpentine or the compositions called driers. 



> The clear oil produced after boiling, even when from the very best makers, 

 always contains a considerable quantity of lead, and is dark-colored al- 

 most black, and does not, on exposure to air, materially bleach. Its rate of 

 drying, per se, is, on an average of the best kinds, fifteen hours ; but more 

 generally ranges between twenty-four hours and sixty hours. 



The oil-boiling trade is divided chiefly between two classes : the paint 

 manufacturers and grinders, who boil oil for their own use and for their own 

 sale ; and the oil boilers and refiners, who receive from the oil merchants 

 and from consumers not themselves boilers the raw oil, put it through 

 the operation, and return it at a certain charge per ton. 



The problem is to take the raw oil and give it an efficient rate of drying 

 property, that can be modified at pleasure ; to give to it any color, ranging 

 between dark brown and straw color ; and to give to it any required degree 

 of limpidity or viscidity that will fit the multifarious requirements of the 

 manufacturer and artist. 



