64 The Raw Matrrial [Feb., 



strong grasp of chemical affinity, they may so strongly retain their 

 places, as to require great force to part them. It also becomes solid, 

 as every one knows, when its temperature is reduced to thirty-two 

 degrees Fahrenheit. In assuming this form, it expands, as many 

 a broken water-pitcher, carelessly left in a cold room during this 

 severe weather, can testify. 



It is this expansive power of freezing water, that renders it such. 

 a useful agent in the preparation of soils. It penetrates easily the 

 soft rocks, and the expansion of the first hard frost crumbles them 

 to dust ; even the solid granite loses by the same process, little by 

 little from its surface, until the whole huge mass is ground into light 

 and mellow soil. Hence, the great advantage of exposing the loosen- 

 ed earth to the thorough action of winter frost, as is frequently 

 done in situations where it will not wash away, by throwing the 

 earth up in ridges in the fall. 



This expansion of water, near the freezing point, prevents our 

 rivers, ponds and lakes from being wholly converted into ice dur- 

 ing our long cold winters, and is often instanced as exhibiting the 

 infinite skill of the Creator in keeping all the parts of this compli- 

 cated machinery in simple harmonious action. 



Were the ice heavier than the water, layer after layer, during a 

 hard frost, would fall to the bottom, until the whole mass would be 

 solidly frozen, and the summer sun would not have power to entire- 

 ly thaw it. 



Salt and Guano. — Recent experiments go to show that com- 

 mon salt is a valuable addition to all applications of guano to the 

 soil. It not only has a pendency to give strength and hardness to 

 the straw, (which guano weakens,) but prevents the loss of ammonia, 

 which is constantly going on, even in a dry atmosphere. M. Barral, 

 the editor of a French agricultural journal, says : — 



" We left in open air, in plates, during fifteen days, equal weights 

 of the pure guano and guano previously mixed with salt. At the 

 end of that time, we examined anew the amount of nitrogen, and 

 found that the pure guano had lost 1 1.6 per cent, of nitrogen, while 

 that mixed with salt had lost only 5 per cent." The refuse salt from 

 fish packers is recommended for this purpose, and any refuse salt 

 would probably answer the purpose. 



