LECTURE XVlll. 



Animal manures.— Flesh, blood, and skin.— Wool, woollen rags, hair, horn, and bones.— On 

 what does the fertilizing action of bones depend 7— Animal charcoal and the refuse of the 

 sugar refineries.— Fish and fish-refuse, whale blubber and oil. — Relative fertilizing value 

 of the substances previously described. — Pigeon dung. — Dung of sea-fowl : guano. — 

 Liquid manures : the urine of various animals. — Mixed animal and vegetable manures. — 

 Night soil, the droppings of the horse, the cow, the pig. — Effects of digestion upon vege- 

 table food. — Why equal weights of vegetable matter, and the droppings of animals fed 



me.— W( 



upon it, possess different fertilizing powers.- Farm-yard dung.— Weight of dung pro- 

 duced from a given weight of grass, straw, and other produce.— Loss undergone by 

 farm-yard manure during fermentation.— Improvement of the soil by irrigation. 



Animal substances have always been considered as more fertilizing 

 to the land than such as are of vegetable origin. Their action is in 

 general more immediate and apparent, and it takes place within such a 

 Innited period of time that the farmer can calculate upon its being ex- 

 ercised in benefitting the crop to which it is applied. The reason of this 

 more immediate action will presently appear. 



§ 1. Of Jiesh, blood, and skin. 



1°. Flesh. — The flesh of animals is not only a rich manure m itself, 

 but the rapidity with which it undergoes decay in our climate enables 

 it speedily to bring other organic substances with which it may be mixed 

 into a state of active fermentation. It is only the flesh of such dead 

 animals, however, as are unfit for food, that can be economically ap- 

 plied to the land as a manure. 



The flesh of animals consists of a lea7i part, called the muscular fibre, 

 or by chemists fibrin, and i\ fatty part, intermixed with the lean in 

 greater or.less proportion, according to the condition of the animal. 

 Of these two it is the lean part which acts most immediately and most 

 energetically in the promotion of vegetation. Lean beef, in the recent 

 state, contains 77 per cent, of its weight of water, so that 100 lbs. consists 

 of 77 lbs. of water and 23 lbs. of dry animal matter. 



2°. Blood. — The blood of animals is more extensively employed as 

 a manure. It is carried ofl'in large quantities from the slaughter-houses 

 of the butchers, and makes rich and fertilizing composts. In some 

 parts of Europe it is dried, and in the state of dry powder is applied with 

 much effect as atop-dressing to many crops. 



Liquid blood consists of fibrin — the substance of lean meat, of albu- 

 men — the same as the white of eggf^ — of a red coloring matter, and of 

 certain saline substances dissolved in a considerable quantity of water. 

 When blood cools it gradually congeals, and separates into two parts, 

 a gelatinous red portion, called the clot, and a liquid, nearly colorless, 

 part called the serum. The clot contains most of the fibrin and color- 

 ing matter, and a portion of the albumen ; the serum, the greater part 

 of the albumen and of the soluble saline substances which are present 

 m the blood. 



The relative composition of fresh muscular fibre and of liquid blood 

 is thus represented in 100 parts : — 

 19* 



