THE YEAR-BOOK OF AGRICULTURE. 



effect upon vegetation. The next ingredient in fiah was the oiL The proportion of this 

 differs verym ich in different fiah. I" the flesh of the herring, 18 per cent hud been found. 

 In the mackerel, Prof. Way had foon 1 aa much as -I! per cent, of oil, or one-fourth part of 

 it- entire weight In this fiah the oil Beemed to substitute part of the water found in other 

 varieties ; for it did not contain more than 41 per cent, of moisture, or two-thirds of that 

 usually present The quantity of nitrogen and <>t' ash was also very large; both of them 

 considerably larger than in any other ti -li id" which the comparison was known. If 

 available in quantities, therefore, this fish would be very valuable for manure. Now, con- 

 ring the large proportion of oil in fish, it became important to consider of what value it 

 might be in manure. It had become the fashion of late years to give too exclusive a con- 

 sideration to the importance of nitrogen in vegetation; not that we could too much value this 

 important element, but that we were in danger "t' neglecting those substances which took a 

 less prominent but a no less necessary part, in the economy of vegetation. That carbona- 

 ceous matter in the soil was beneficial, if not indispensable, to profitable cultivation, did not 

 seem to admit of a doubt; and if so, there might be clearly a choice between carbonaceous 

 substances, according to their rate of decomposition, &c. Now oils were very susceptible 

 of oxidation, with the production, of course, of carbonic acid. He might only mention in 

 illustration, the spontaneous combustion often occurring when oily rags used for machinery, 

 &c. had been thrown into a heap, and by the absorption of oxygen and heat consequent 

 thereupon, it had, in many cases, caused great destruction of property. 



Then again, the manufacture of "drying oils," as they were called, by boiling linseed and 

 other oils in contact with the air, the experiments of Saussure, who placed different oils 

 under receivers of air, and found at the end of the experiments that all the oxygen had 

 become carbonic acid at the expense of the oil, were also to the purpose. Now it was < 

 to see that oil distributed through a porous soil would, on account of the great surface 

 exposed, suffer rapid oxidation, and give off a ready supply of carbonic acid, which at par- 

 ticular periods of their growth might be most important to some plants. 



Mr. Way quoted passages from the work of Dr. Home, printed in L762, and the "Georgical 

 E ays" of Dr. Hunter, a few years later, to show that a very high opinion of the value of 

 oil a- manure was held by early writers. He also referred to the experiments of Karl Spen- 

 cer with oil, to the use of whale-blubber, which, however, no doubt owed much of its value 

 to the flesh. II' showed also that many of the substances known as powerful manures, and 

 taining nitrojr C nous matter, also contained oil. Thus woollen rags, rape-cake. &C. might 

 owe part of their efficacy to this cause. Rape-cake contained about 4 per cent, of nitrogen, 

 while its oil varied from 12 to 15 per cent. 



On the uli.le. this subject of oil, as manure, was well worth looking into; not that oil 

 Would be likely to be u-ed directly :i - a manure, (its value for other purposes being Opp< 

 to BUOb a ase of it.) but that we might be able to value more correctly BUbstanceS in which 

 Occurred, and OOUld not profitably be extracted, as suitable for manure. The other main 

 ingredient of fish was the ash or mineral matter, which, although of less importance than 



the others, (on account of the smaUness of it- proportion,) was not to be overlooked. Mr. 

 AVav ben ad to the analyses of different fiah, showing thai la the lobster the quantity 



of phosphate of lime was ai much as ', p#T cent, of the fish in its dried state, and about the 

 Same in the mackerel: this pho-phate of limo SOUld DOl be without its u 



Mr. Way next directed attention to the various methods of preserving fiah that had been 

 proposed, including those of Mr. petit, by sulphuric add : of Mr. Elliott, by the use of alkali ; 

 of Mr. B tie ll, by the employment of tar-oils; andofM.de Moloas, by treatmencwith high- 

 pressure steam. He also mentioned the plan which irai adopted by a manufacturer of 

 manun evens,) who had a contract tor the refuse fisb of Billingsgate mai ket of inoor- 



iting the fish in Super-phosphate of lime, the quantity Of water in th< rving to 



dilute the mid, and being dried up by the natural heat of the p He remarked, how- 



. that there would be no difficulty in preserving the fiah, if i' could be obi lined. It was 

 nob a que 'ion of thi- or that process, but of the supply of raw material. He c 

 not help believing that this was not :m insuperable difficulty, if systematic mi were 



• n to effect the purpose. Was it affirmed that our system of taking fish was incapable of 



