| Olive oil consists of | 77 | ·2 | carbon, | 13 | ·4 | hydrogen, and | 9 | ·4 | oxygen, in 100 parts. | |||||||
| Spermaceti oil, | by my analysis, of | 78 | ·9 | carbon, | 10 | ·97 | hydrogen, and | 10 | ·13 | oxygen. | ||||||
| Castor oil | do. | 74 | ·0 | 10 | ·3 | 15 | ·7 | azote, | ||||||||
| Stearine of olive oil | 82 | ·17 | 11 | ·23 | 6 | ·30 | 0 | ·30 | Saussure. | |||||||
| Oleine of olivdo. | 76 | ·03 | 11 | ·54 | 12 | ·07 | 0 | ·35 | do. | |||||||
| Linseed oil | 76 | ·01 | 11 | ·35 | 12 | ·64 | do. | |||||||||
| Nut oil | 79 | ·77 | 10 | ·57 | 9 | ·12 | 0 | ·54 | do. | |||||||
| Oil of almonds | 77 | ·40 | 11 | ·48 | 10 | ·83 | 0 | ·29 | ||||||||
De Saussure concludes that the less fusible fats contain more carbon and less oxygen, and that oils are more soluble in alcohol, the more oxygen they contain.
I shall now take a short view of the peculiarities of the principal expressed oils.
Oil of almonds, according to Gusseron, contains no stearine; at least he could obtain none by cooling it and squeezing it successively till it all congealed. Braconnot had, on the contrary, said, that it contains 24 per cent. of stearine. I believe that Gusseron is right, and that Braconnot had made fallacious experiments on an impure oil.
Oil of colza, is obtained from the seeds of brassica campestris, to the amount of 39 per cent. of their weight. It forms an excellent lamp oil, and is much employed in France.
The corylus avellana furnishes in oil 60 per cent. of the weight of the nuts.
Hempseed oil, resembles the preceding, but has a disagreeable smell, and a mawkish taste. It is used extensively for making both soft soap and varnishes.
Linseed oil, is obtained in greatest purity by cold pressure; but by a steam heat of about 200° F. a very good oil may be procured in larger quantity. The proportion of oil usually stated by authors is 22 per cent. of the weight of the seed; but Mr. Blundell informs me, that, by his plan of hydraulic pressure, he obtains from 26 to 27. In the Encyclopædia Metropolitana, under Oil Press, a quarter of seed (whose average weight is 400 lbs.) is said to yield 20 gallons of oil. Now as the gallon of linseed oil weighs 9·3 lbs., the total product will be 186 lbs., which amounts to more than 45 per cent.—an extravagant statement, about double the ordinary product in oil mills. Even supposing the gallons not to be imperial, but old English, we should have upwards of 38 per cent. of oil by weight, which is still an impossible quantity. Such are the errors introduced into respectable books, by adopting without practical knowledge, the puffing statements of a patentee. It dissolves in 5 parts of boiling alcohol, in 40 parts of cold alcohol, and in 1·6 parts of ether. When kept long cool in a cask partly open, it deposits masses of white stearine along with a brownish powder. That stearine is very difficult of saponification.
Mustard-seed oil. The white or yellow seed affords 36 per cent. of oil, and the black seed 18 per cent. The oil concretes when cooled a little below 32° F.
Nut oil, is at first greenish coloured, but becomes pale yellow by time. It congeals at the same low temperature as linseed oil, into a white mass, and has a more drying quality than it.