GUANO, BONE?.] AGRICULTURE 347 to mislead the public mind. We offer these remarks in no spirit of hostility to this new system of farming. We shall rejoice unfeignedly to find that our opinion of it is erroneous, and that it really warrants the sanguine expectations which some parties entertain regarding it. We simply maintain that as yet the case is " not proven," and our counsel to those who are disposed to try it is, not to embark in it to an extent that would embarrass them, if, as we fear, it should prove a failure. Section 3. Guano. Next to farm-yard manure, which must ever be looked to as the chief means of maintaining the fertility of a farm, guano claims our notice. This substance is the dung of seafowl, and is found on rocky islets in parts of the world where rain seldom falls. The droppings of the myriads of birds by which such places are frequented have in many cases been permitted to accumulate during untold ages, and are now found in enormous deposits. The principal supply, both for quantity and quality, has hitherto come from the Chincha Islands, on the coast of Peru. The introduction of this powerful and exceedingly portable manure gave a prodigious impetus to agricultural improvement. It is about thirty years since a few casks of this article were brought to Liverpool from Peru, where it has been known and prized as a valuable manure from the remotest periods. No sooner had its value been discovered by our British agriculturists than the demand for it became so keen, that the quantity imported rose from 2881 tons in 1841 to 283,300 tons in 1845. The price at which it was sold at first was 20 per ton, from which, with increased supplies, it fell to 11, when the discovery in 1844 of a considerable deposit on the island of Ichaboe, on the coast of Africa, at once reduced the price to 9. Discoveries have from time to time been made of other deposits on the African coast and in Australia. The quality of both is nruch inferior to that from Peru. It is in a more advanced state of decay, and contains more moisture and sand. Great as was the deposit of this valu able fertiliser on the Chincha Islands, it rapidly diminished under the excessive demand for it from Great Britain and other countries. Gradually the quality became very in ferior, and in 1871 it was announced that this deposit was entirely exhausted. Considerable supplies are still obtained from other parts of the Peruvian coast ; but unfortunately the quality is very inferior to that formerly obtained from the Chinchas. This circumstance would not be of much consequence if the guano was offered for sale on fair terms ; but as the agents of the Peruvian Government sell it only at one uniform price per ton, although different cargoes, and even different portions of any one cargo, vary excessively in quality, it is now an unsafe article for farmers to purchase. We give here, from the Board of Trade returns, a table of the quantities of guano imported yearly, with the com puted real value, from 1854 to 1872. Table showing Ike Imports of Guano from 1854 to 1872. Tear. Tons. Value. Year. Tons. Value. 1854 235,111 2,530,272 1864 131,358 1,457,088 1S55 305,061 3,137,160 1865 237,393 2,675,995 1856 191,501 2,136,431 1866 135,697 1,439,679 1857 288,362 3,613,074 1867 192,308 2,109,506 1853 353,541 4,084,170 1868 182,343 2,039,478 1859 I860 84,122 141,435 769,333 1,557,895 1869 1870 210,010 280,311 2,640,983 3,476,680 1861 178,423 2,022,283 1871 178,678 1,994,145 1862 141,636 1,635,322 1872 118,704 1,201,042 1863 233,574 2,658,856 The dung of birds, from its including both liquid and solid excrements, is superior as a manure to that of quadru peds. Pigeons dung has long been in high repute as an excellent fertiliser, and brought a high price in days when portable manures were scarcely to be had. It is now little heard of, guano, the excrement of fowls which feed upon fish, being superior, weight for weight. The dung of domestic poultry is usually mixed with the general dung- heap, but it could be turned to better account if kept by itself. It has been recommended to strew the floors of poul try-houses daily with sawdust or sand, and to rake this with the droppings into a heap to be kept under cover and used like guano. Section 4. Bones. It is now about sixty years since ground bones began to be used by farmers in the east side of England as a manure for turnips. At first bones were roughly smashed by ham mers and applied in great quantities. By and by mills were constructed for grinding them to a coarse powder, in which state they continued to be used as a dressing for turnips, at the rate of sixteen to twenty bushels per acre, in all parts of the kingdom and to a very great extent, until the ad mirable discovery by Baron Liebig of the mode of preparing superphosphate of lime by dissolving bones in sulphuric acid. We shall not attempt to explain on chemical princi ples the wonderful superiority of this substance over simple bone-dust in promoting the growth of the turnip plant. What we should do indifferently, by borrowing from others, will be found well done by various accomplished chemists who write specially on these subjects. We can, however, testify from experience to the important fact, that one bushel of bone-dust dissolved by a third of its weight of sulphuric acid is as a manure superior in value to four bushels of simple bone-dust. It is not merely, or even chiefly, in the lessened cost at which an acre of turnips can be manured that this superiority lies, but especially in this, that from the extraordinary stimulus given by superphosphate of lime to newly germinated turnip plants, they usually arrive at the stage when they are fit for thinning in from ten to fifteen days earlier than when sown over farm-yard dung or simple bone-dust, or both combined. This shortening of the critical period during which the attacks of the insignifi cant but dreaded turnip-beetle so often baulk the hopes of the husbandman is an advantage not easily estimated, and one well fitted to inspire him with confidence in the science to which he owes the discovery, and with grateful respect for the eminent discoverer. This powerful effect in quicken ing the growth of the young turnip plants is possessed in nearly as great a degree by Peruvian guano, when it is supplied with sufficient moisture. In climates and seasons which may be characterised as moist and cool, guano will show best results, whereas in those which are rather hot and dry superphosphate has the advantage. Accordingly we find guano the comparative favourite in Scotland, and it& rival in the drier counties of England. Guano is believed to encourage a great expanse of foliage, and to be more especially suited for early sowings ; and superphosphate to influence development of bulb, and to deserve the preference for a later seed-time. The obvious inference is that, for the turnip crop at least, these valu able fertilisers should be used in combination ; and actual experiment has verified its soundness. The use of them is universal and ever on the increase. They constitute also the standard by which farmers estimate the cost and effects of other purchased manures. The extent to which they are used, their high price, and the facility with which they can be adulterated with comparatively worthless ingredients, have led to almost unparalleled frauds. The adulteration of manures has, in fact, become a regular trade. Had farmers only their bodily senses to aid them, the detection
of this fraud would be difficult perhaps impossible. Here,
