AGRICULTURAL CHEMISTRY AND GEOLOGY. 189 



For this reason the dryness of a salt is an excellent criterion of its purity, and, in the ab- 

 sence of an analysis, may serve to guide the purchaser. 



As far as the use of salt for the dairy is concerned, it seems obvious that we must mainly 

 depend on its purity; and it was, doubtless, for this reason that bay-salt was formerly 

 preferred. 



It is necessary to be remai'ked, however, that the form of the salt is not immaterial ; and 

 that when in fine powder it is clearly preferable to large grains or crystals, and that because 

 it admits of more thorough incorporation with the butter, and its antiseptic effects will be 

 secured by the use of a smaller quantity than would be necessary if in large crystals. 



As a general rule, the salt now met with in commerce is very fine ; but instances are some- 

 times met with in which the magnesia salts are present in considerable quantity. I have 

 seen specimens containing as much as 3 per cent, of chloride of magnesium and sulphate 

 of magnesia, and such samples contain much water ; so that the amount of pure salt does 

 not exceed from 89 to 90 per cent. 



Such salt should be carefully avoided for dairy purposes ; and all care should be taken to 

 obtain it as pure as possible. Prof. Anderson, Highland Ag. Soc. 



Qualities of Pasturage. 



THE following remarks on the qualities of pasturage are taken from the Transactions of 

 the Croyden Farmers' Club, England : 



What is the cause that some pasture will readily fatten stock fit for the butcher, while others, 

 with an tt'inndance of grass, will only keep stock merely in a growing or thriving condition? 



That such is the fact, all farmers are and have been aware of for ages past, but as to the 

 > of these differences no good or sufficient reason has been assigned. I will, however, 

 state what I consider an explanation why the one does fatten so readily, and why the other 

 does not, and also give reasons and authorities for such opinions. First, the tutu-uing quali- 

 ties of what are termed rich grazing lands may probably be owing to all the several elements 

 of nutrition being present in such quantities in relation to each other, and in states of com- 

 binsitiou, that are well adapted for being assimilated and deposited as fat and muscle, thereby 

 requiring no unnecessary expenditure of the vital power or principle to produce such effect. 



Dr. Thomson, in his "Experimental Researches on the Food of Animals," says "Besides 

 the necessity for the presence of the same materials in the food which exist in the blood, it 

 is requisite that each should bear a certain relation to the whole." Now it is reasonable to 

 think that it is so, and also that where one or more elements in the food are in excess, that 

 there must be an expenditure of vital power to get rid of such excess. 



Prof. Johnston also says "It has been ascertained by physiologists that all the parts of the 

 body undergo a slow and sensible process of renewal, the place of that which is removed 

 being supplied by new portions of matter derived from the food, and that this renewal goes 

 on so rapidly, that in the space of time the whole body of the animal is renewed. I may 

 observe that we know by experience when a rich pasture is broken up, it takes many years 

 when again laid down to pasture before it at all approaches to its former fattening powers, 

 and also before it again produces all those numerous grasses (if ever it does again) which 

 grew upon it before it was broken up. There may be another cause which aids in the fatten- 

 ing qualities of such pastures ; and that is the presence of some plant or plants containing one 

 or more of those classes of compounds which have the property of changing one compound 

 into another, thereby saving an expenditure of the vital power in digestion." 



Why is it, that the majority, I may say, of meadows which produce an ample crop of 

 herbage to satisfy the appetite of animals grazing thereon, will not fatten them fit for the 

 butcher without the aid of some artificial food ? Here again, as in the former case, we can 

 only conjecture. We are certain that all the elements requisite to form the animal are pre- 

 sent in the herbage and hay grown thereon, from the fact that animals bred on, and fed 

 upon, the produce of such pastures or meadows come to full maturity in health and strength ; 

 still, it does not follow that the several quantities of these elements are in such a relation to 

 each other, and in such combinations of forms, as not to require considerably more expendi- 



