THE FARMER'S MAGAZINE. 



285 



mer, living near a small town, might advantageous- 

 ly contract to take the whole of the blood at this 

 price. There are many other sources of animal 

 matters which will at once occur, available for 

 manures. Of these, we may particularise the 

 refuse of glue and oil-boiling works, which yield, 

 annually, a considerable quantity of nitrogeous 

 oiFal ; and the two analyses of seal and glue refuse 

 which follow will show that, even when they are 

 prepared without much care, they may become 

 useful manures : — 



Seal Refuse. Glue Refuse. 

 Ash . . . 36.81 . . 53.18 

 Organic matter 41.85 . . 38.60 

 Water . .21.34 . . 8.22 



100.00 100.00 



Ammonia . 2.24 . . 2.00 

 The large quantity of ash in these cases is due to 

 the admi.xture of earthy matters, for the purpose of 

 drying up and rendering portable the animal mat- 

 ter ; and, though this has not been done in the 

 most suitable manner, the value of the manure is 

 about five times as great as that of good farmyard 

 manure.— Professor Anderson, in the Trans- 

 actions of the Highland Society.. 



GRINDING FEED. 



Experimental farmers have long urged the im- 

 portance, and even necessity, of chopping or 

 grinding hay, as well as other food, for cattle and 

 horses. The lazy drones have had a hearty 

 laugh over the idea, and called it " Book Farm- 



Now the theory of chopping and grinding food 

 is based on a principle which lies at the foundation 

 of animal physiology. Rest is essential to the 

 accumulation of muscle, as well as fat. If we wish 

 to increase an animal in flesh or fat, we do not 

 work him. 



Now a cow wants one-thirtieth of her own 

 weight in hay a day, to keep her in good order ; 

 and we may thus calculate the amount of labour re- 

 quired to masticate the food, and fit it for the 

 stomach. The labour of chopping or grinding 

 twenty-five pounds of dry hay a day, is no small 

 item. This excessive labour is performed by one 

 set of muscles — the jaws ; but, by sympathy, affects 

 all the other muscles ; causes the blood to circulate 

 quicker, the breath faster, the consumption of 

 food greater ; and still the growth of the animal is 

 retarded. 



If a machine was invented to grind hay, the 

 ground article would approximate, in value, to un- 

 ground oats, in producing fat and muscle. Chop- 

 ping hay and stalks is valuable just in proportion 

 as it approximates to grinding, and relieves the 

 animal of the labour of grinding it. An animal fed 

 on ground or minced food may perform an 

 amount of labour equal to grinding it fit for diges- 

 tion, and fat as fast as another which does not 

 labour, but grinds its own food. 



Prematurely grey whiskers and beard, while the 

 hair is still black, show the relative amount of labour 

 performed by the jaws and the head. 



LIME, AND ITS CHEMICAL CHANGES. 



Lirae is uot, as it was once supposed, an element, but consists 

 of the metal calcium united with the gas oxygen, and is pro- 

 perly an oxide of calcium, just as potash, soda, and magnesia 

 are oxides of potassium, sodium, magnesium. It is never found 

 pure in nature, except occasionally in the craters of volcanoes, 

 but is usually united with carbonic acid, for which it has a 

 strong attraction. In this state it is neutral, and insoluble in 

 pure water. When limestone or any other form of carbonate 

 of lime is exposed to a sufficiently hi;;h temperature with 

 access of air or moisture, the carbonic acid gas is driven off, 

 and the lime which reaaains is called qxdch or caustic, from its 

 strong alkaline re-action. When such lime is plunged into 

 water for a short time, or water is poured upon it, heat is 

 evolved, the lime swells, cracks, gives off much watery vapour, 

 and finally falls to a powder. This powder or slaked lime is a 

 hydrate of lime, water being chemically combined with it. In 

 this state it is still caustic, though somewhat milder than when 

 fresh from the kiln. 



The rise of temperature is so great when large heaps of good 

 lime are suddenly slaked, as to enflame gunpowder aud scorch 

 wood ; it certainly exceeds, according to Pelletier, 500° ; and 

 when the operation is performed in a dark place, light is also 

 evolved. All sorts of imaginary causes have been assigned to 

 account for these phenomena. They are referable, however, 

 to a very simple and universal law. All substances during 

 their change from a gaseous to a liquid, or from a liquid to a 

 solid stale, evolve heat, and vice versa. The intense cold pro- 

 duced by liquefying ice or snow by admixture with salt is a 

 familiar instance of the latter ; and the heat evolved in solidi- 

 fying carbonic acid under intense cold and pressure is some- 

 times dangerous evidence of the former — the expansion of air 

 consequent on the sudden liberation of heat from the carbonic 

 acid in the moment of congelation not unfrequently shattering 

 the vessel to atoma. 



Lime in slaking will absorb one-fourth its weight of water ; 

 but the slaked lime is not more moist than before. The water 

 unquestionably, therefore, is chemically combined with the 

 lime, and becomes solidified ; and it is simply owing to this 

 solidification of the water that heat is evolved. 



Caustic lime has a strong affinity for water and carbonic 

 acid. When kept in a dry place it gradually slakes, cracking, 

 splitting, and crumbling to powder with the evolution of heat 

 — which, however, is not so perceptible on account of the 

 length of time during which the process is extended— just as 

 though it had been slaked by pouring on water. lu this case 

 the lime has obtained from the atmosphere the 25 psr cent, 

 of water it needs to slake it. There is this difference, how- 

 ever, between air-slalced lime and that which is water-slaked : 

 the former is slaked precisely as the latter, by the absorption 

 of water, but it also absorbs carbonic acid from the air, and 

 instead of being simply a hydrate of lime as when water-slaked, 

 it is a definite compound of hydrate and carbonate of lime, 

 42.6 per cent, of the former, and 57.4 of the latter. Air slaked 

 lime, therefore, is far from being so caustic as water-slaked, 

 upwards of one-half of it being reconverted into the same 

 chemical state as it was in before burning. 



A fter the lime has absorbed sufficient water and is completely 

 fallen to pieces, carbonic acid is absorbed much less rapidly, 

 especially in damp situations. In fact, though there is a con- 

 stant tendency in lime to return to the state of carbonate in 

 which it existed previous to burning, yet, by mere exposure to 

 the air, it does not attain this state in any assignable time. 



