160 THE YEAR-BOOK OF AGRICULTURE. 



and cavities lined with crystals, are all according facts in favor of the conclusion adopted. 

 The experiments, in their extended application to other aggregates, are proving that many 

 compact rocks may be formed at common temperatures by a similar action, not always in- 

 volving a chemical solution of the materials. 



On the Mixing of Common Salt and Guano, 



THE following experiments, performed by Mr. Barral, editor of the Journal tf Agriculture 

 Pratique, prove the value of common salt as a fixer of ammonia. M. Barral took two sam- 

 ples of guano : the one he kept pure the other he 'mixed with a refuse salt obtained in the 

 manufacture of gunpowder, (and consisting principally of common salt with a small quan- 

 tity of saltpetre, nitrate of potassa,) in the proportion of 50 per cent, of this salt. "The 

 sample of pure guano which we analyzed," says M. Barral, "contained 12-56 per cent, of 

 nitrogen ; the sample mixed with salt contained only 6-23 per cent. We do not take into 

 account the nitrogen in the state of nitrate mixed with the salt. We subjected equal weights 

 of the two samples to heat for three hours in the same stove, in a current of air, maintained 

 at 100. They were spread out so as to have the same thickness, and occupy an equal sur- 

 face, and they had been equally pulverized. At the end of the three hours, on examining 

 the two samples, we found that the pure guano had lost 5'7 per cent, of its nitrogen, while 

 the mixture had lost only 1-9 per cent, of its nitrogen. 



" Though this experiment appeared to us to be in favor of the preservative power of salt, we 

 repeated it under another form. We left in the open air, in plates, during fifteen days, equal 

 weights of the pure and the mixed guano. At the end of that time we examined anew the 

 amount of nitrogen, and found that the pure guano had lost 11-6 per cent, of its nitrogen; 

 while that mixed with salt had lost only 5 per cent. Thus we see salt can be usefully 

 employed for mixing with guano." 



This property of salt, as a fixer of ammonia, has not been sufficiently attended to in agri- 

 culture. While chemists recommend gypsum, nitrate of lead, chloride of zinc, sulphate of 

 iron, and chloride of manganese for this purpose, common salt is but rarely alluded to. It 

 has been used extensively of late, with nitrate of soda as a top dressing, with the view of 

 strengthening the straw of the cereals. It has been alleged that guano tends very much to 

 increase the growth of vines in the potato crop. We are of opinion, from numerous experi- 

 ments before us, that, when applied to this crop, the guano should always be mixed with 

 some fixer of the ammonia, such as gypsum, salt, or charcoal: at present prices, the most 

 expensive of these, at the rate of one hundredweight per acre, will not cost more than 2s. per 

 acre. Another important fact, independent of the value of the salt, brought out by M. Bar- 

 ral' s experiment, is the great waste of ammonia which takes place on exposing guano to 

 the air. It will be remarked that, in the case before us, upwards of one-tenth of the 

 nitrogen was lost in the course of fifteen days. This shows the necessity of farmers hus- 

 banding as much as possible this important ingredient of their manure. Instead of throwing 

 their guano in exposed sheds, as is too often done, it should be carefully covered up, and 

 mixed, immediately on their receiving it, with some preserver of its ammonia. 



Superphosphate of Lime for Root Crops. 



SUPERPHOSPHATE of lime is used to a great extent in England as a manure for turnips, ruta 

 bagas, mangel-wurzels, and other root crops. When sown broadcast, it has very little influ- 

 ence on the crop ; but when drilled with the seed its effects are oftentimes astonishing. Philip 

 Pusey and some others have shown, too, that, when the superphosphate is dissolved in water 

 and applied in the seed-drills in a liquid form, the effect is still more beneficial. Alfred S. 

 Ruston, in the London Farmer's Magazine, gives the results of some carefully-conducted 

 experiments on the subject. There were seven separate experiments made ; but. as the results 

 agree pretty closely, we select one as a sample of the whole. 



Three plots were dressed with eleven loads of barn-yard manure per acre, thrown into 

 ridges, and sown with mangel-wurzels, April 17th. The first plot received no artificial 



