CHEMISTRY OF HORTICULTURE. LIME. 
325 
first to try the fertilising power of Gypsum upon Clover. “ He sowed it on a field near 
one of the high roads of Pennsylvania, and formed the letters of a sentence like the 
following — ‘ This is manured with Gypsum.’ The effect was such that the letters could 
be readily distinguished by the height and colour of the Clover where the Gypsum had 
been sown. This naturally drew attention, and from that time it appears that gypsum 
has been regularly imported into America for manure from Havre.” 
In England its effects are most perceptible in light loams, gravels, and sands, where 
much vegetable earth is present. 
Phosphate of Lime. — Bone-earth or bone phosphate. There are several combinations 
of lime with phosphoric acid ; but the circumstance most interesting to the cultivator is the 
great natural fact, that the phosphoric acid evinces a strong tendency to form a basic- 
salt with lime. Bones contain a very large proportion of this basic-salt. Guano of good 
quality comprises from 10 to 25 per cent of it, and in a state of extreme fine division. 
It occurs abundantly in the Coprolithic deposits that have lately been discovered, and in the 
minerals known under the names of Apatite , Asparagus-stone , Moraxite, and Phosphorite. 
It is generally crystalline and massive ; the variety found in Cornwall and Devonshire is 
beautiful, its primitive form a six-sided prism. Thus nature has, as it were, pointed out 
to man, by the abundant store of it which she provides, the very great value of the basal 
phosphate of lime. At a very high temperature it fuses into a white, opaque, or semi-trans- 
parent enamel ; hence, in the manufacture of china, bones deprived, by distillation, of 
their animal fat and ammonia, are largely introduced in preparing the “ china body ” of 
the potteries. 
Animal bones are found to consist pretty nearly of 
Solid Cartilage, Gelatine, and Oil . . . . . .51 percent. 
Phosphate of Lime ......... 37*7 „ 
Phosphate of Magnesia . . . . . . . . l - 3 „ 
Carbonate of Lime . . . . . . . ..10 „ 
100 - 
The animal matter contains much nitrogen, hydrogen, and oxygen. In distillation, 
the two former unite to produce ammonia ; the two latter to produce water — both, of course, 
combining in their proper equivalent proportionals. Thus, the liquor formerly called 
hartshorn, is produced from bones, and with it a quantity of empyreumatic animal oil. 
The basal phosphate, &c., left in the retorts, on being drawn from them while red hot, take 
fire owing to the combustion of some remaining animal matter, and finally become white. 
When bone-dust came into use on the farm, a vast quantity of Turnips was produced ; 
and, as a natural consequence, numbers of experiments were performed with a view to 
ascertain how, where, and to what extent this animal manure could with safety and 
efficiency be employed in Turnip culture. “ The Book of the Farm ” first appeared in the 
year 1844; its second edition is now in the course of publication, and, to a safer or more 
experienced instructor, I think it will be impossible to appeal, than to Mr. Henry Stephens 
of Edinburgh, its author. 
“ There is something,” he observes, “ in the action of bone-dust on the soil, and its 
consequent power to produce a Turnip crop, which I do not understand, the means being 
so inadequate to produce the results obtained. What I mean is, that up to a certain 
quantity this manure has evidently a beneficial effect ; but, beyond that quantity, there is 
derived from its use no apparent benefit, in as far at least as the crop is concerned. I 
have tried to raise Turnips with quantities of bone-dust from 12, 16, 20, and 24 bushels 
to the imperial acre, and have found the crop improved up to 16 bushels ; but any quantity 
beyond that, even 24 bushels, produced no greater effect on the Turnips in the same field, 
and on the same sort of soil, than 16 bushels ! ” This passage, be it observed, was printed 
in 1844, and five years have subsequently elapsed. In that short period chemical science 
has been brought into action, and has so far triumphed, that we are now enabled to pursue 
inquiries in a right direction ; for we are now taught to seek for the operation of manure 
in the constituents of plants. Organic analysis was then scarcely thought of in reference 
