( 432 ) [July, 



CHRONICLES OF SCIENCE. 



I. AGRICULTURE. 



In the current number of the ' Transactions of the Highland and 

 Agricultural Society,' Professor Thomas Anderson has described his 

 experiments on the action of uric acid as a manure. They are of con- 

 siderable importance as illustrating the fertilizing action of guano. 

 Of this, indeed, agriculturists need no other proof than that which 

 their own experience offers ; but for harmonizing this experience with 

 the theory of manures, any attempt must do valuable service which 

 shall ascertain the influence upon the growth of plants exercised by 

 those other nitrogenous ingredients of guano, which are present in 

 addition to its ammonia. It is because Liebig had declared that in 

 discussing the value of Peruvian guano as a manure the nitrogen 

 present in its uric acid should not be taken into account, that Dr. 

 Anderson has made it the subject of his present research. 



Peruvian guano, guano ash, uric acid, and sulphate of ammonia, 

 were the materials employed in his experiments. The first formed 

 the standard, and it was contrasted first with a mixture of its own ash 

 with uric acid in such proportion as to contain exactly the same quan- 

 tity of nitrogen as the guano itself did, and next with a similar mixture 

 of the ash with sulphate of ammonia. The crops (turnips and wheat) 

 thus received in every case exactly the same quantities of mineral 

 matters and of nitrogen, but the latter element existed in one case 

 entirely as uric acid, in another entirely as sulphate of ammonia, and 

 in the guano itself partly as ammonia and partly as uric acid. The 

 results on the turnip crop were obtained from a late sown crop, and 

 are so far not altogether satisfactory ; they proved in every case the 

 mixture of guano, ash, and sulphate of ammonia to be best ; then the 

 guano itself ; and lastly, the guano ash, and uric acid. The conclu- 

 sion here, therefore, was favourable to the ready formed ammonia as a 

 source of nitrogen. It is not, however, upon the turnip crop, but upon 

 the grain crop, that the true effect and influence of nitrogenous 

 manures is to be read. And on the wheat crop it appeared that the 

 guano ash by itself was entirely without effect ; the produce, where it 

 alone was used, being no better than where nothing at all had been 

 applied. In every case, however, the nitrogenous manure produced a 

 very marked increase in the crop, and but little difference was 

 observable in the action of the guano, the uric acid, and the sulphate 

 of ammonia. In one set of experiments the guano was best, the sul- 

 phate of ammonia next, and the uric acid third. In another series, 

 the uric acid was first, the sulphate of ammonia second, and the guano 

 third. Taking the average of the two series, the produce per acre 

 of equal quantities of nitrogen in the manure, in the form of uric acid, 

 was 50*9 bushels per acre; in the form of guano, it was 49*8 



