POU 



PR A 



The uric acid by decay becomes ! 

 converted into bicarl)onale of amnio- 1 

 nia, so tiiat the manure is nearly ap- 

 proaciiing to commercial carbonate ! 

 of ammonia, with a litiie bone earth. 

 Four or five bushels com|M)sted with 

 moist charcoal, gypsum, and peat, 

 and allowed to rot partially, forms a 

 very stimulaiinjr application to young 

 plants and seeds, being as good as 

 about one half the quantity of guano. 

 Johnstone makes the following re- 

 marks on the comparative value of the 

 different kinds of dung, hut it is to be 

 remembered that fowls fed on in- 



sects or animal matters will make 

 manure as rich as guano. 



"Pigeons' (lung is much prized as 

 a manure, wherever it ran be obtain- 

 ed in any considerable (juantity. In 

 Belgium it is esteemed as a top-dress- 

 ing for the young flax, and the yearly 

 produce of 100 pigeons is sold for 

 al)out 20s. Its immediate effect de- 

 pends npon the (juantity of soluble 

 matter it contains, and this varies 

 much, according to its age and to 

 the circumstances under which it has 

 been preserved. Thus, Davy and 

 Sprengel obtained respectively of 



Soluble matter in pigeons' dung 



23 



Recent. Si.T montlis old. 



(D.ivy.) (Sprengel.) 



per cent. Itj per cent. 



After fermentation. 



(Davy.) 



8 per cent. 



"The soluble matter consists of 

 uric acid in small tjuantity, of urate, 

 sulphate, and especially of carbonate 

 of ammonia, conmion salt, and sul- 

 phate of potash ; the insoluble chiefly 

 of phosphate of lime, with a little 

 phosphate of magnesia, and a varia- 

 ble admixture of sand and other 

 earthy matters. When exposed to 

 moisture, the pigeons' dung, especial- 

 ly if recent, undergoes fermentation, 

 loses a portion of its ammoniacal 

 salts, and thus becomes less valuable. 

 When it is intended to be kept, it 

 should be mixed with a dry vegetable 

 soil, or made into a compost with 

 earth and sawdust, with a portion 

 of pulverized or charred peat, or 

 with such a disinfecting charcoal as 

 that which is employed in the man- 

 ufacture of animalized carbon. 



'•Fowl dung often accumulates, 

 decomposes, and runs to waste in 

 poultry-yards, when, with a little care, 

 it might be collected in considerable 

 quantities 



" Goose dung is less rich than that 

 of hens or pigeons, because this bird 

 feeds less upon graifl, and derives a 

 considerable portion of its nourish- 

 ment from the grass which it crops 

 when allowed to go at liberty over 

 the fields. Its known injurious ef- 

 fects upon the grass on which it falls 

 arise from its being in too concen- 

 trated a state. In moist weather, or 

 where rain soon succeeds, it does no 

 injury, and even when in dry weath- 

 634 



er it kills the blades on which it 

 drops, it brings up the succeeding 

 shoots with increased luxuriance." 



POUND, LB. The avoirdupois 

 contains 16 oz. and 7000 troy grs. 

 The troy pound 12 oz. and 5760 grs. 

 Also, an enclosure for cattle. In 

 England a penal enclosure for tres- 

 passing cattle. 



POU PART'S LIGAMENT. A 

 tendinous expansion, running from 

 the top, or crista, of the ilium to the os 

 pubis, under which hernias protrude. 



POVERTY GRASS. Aristida 

 dichotoma. A grass growing on steril 

 places. 



POWER. In mechanics, denoting 

 a force which, being applied to a ma- 

 chine, tends to produce motion. A 

 mcclnuucal poirer denotes one of the 

 six simple machines, viz., the Ici-a; 

 the inclined -plane, the screic, the wheel 

 and axle, the wedge, and the pulley. 



POZZUOLANA. Volcanic ashes, 

 used in making hydraulic cements. 



PR.-ECORDIA. The fore part of 

 the chest. 



PR.EMORSE, BITTEN. Stumpy 

 roots which appear to have been 

 bitten. 



PRAIRIE. This name is given to 

 the immense tracts of grass land oc- 

 curring throughout the West. They 

 are usually gently rolling or undula- 

 ting lands, the grass of which is 

 thickly matted, and from a few inches 

 to three or four feet high, being most 

 luxuriant in wet, swampy places. 



