326 
CHEMISTRY OF HORTICULTURE. LIME. 
to vegetable elements ; now, however, it has been successfully appealed to, and thus the 
component elements of Turnip-tops, when reduced to ash, have been ascertained. 
From one analysis of 100 parts, Professor Johnston has tabulated — 
Potash 
Soda 
Lime 
Magnesia 
Oxide of Iron 
Phosphoric Acid 
Sulphuric Acid 
Chlorine 
Silica 
28-65 
5-41 
23-27 
3-09 
0-86 
9- 29 
12-52 
1605 
0-86 
100-00 
The ash left by burning the dry leaves of the Cabbage yield the following ingredients, 
according to the analysis of Dr. Fromberg : — 
Potash 
Soda 
Lime 
Magnesia 
Oxide of Iron 
Phosphoric Acid 
Sulphuric Acid 
Chlorine 
Silica 
100-00 
11-70 
20-42 
20 - 97 
5-94 
0-60 
12-37 
21 - 48 
5-77 
0-75 
Thus, allowing for quantitative differences, we discover the food that plants require ; 
and as it is certain that the native insoluble earths cannot enter into the structure, or form 
the nutritive juices of vegetables, the cultivator will gradually acquire certain principles by 
which to regulate his order of manuring. Phosphoric acid and lime are found in plants of 
the Brassica family, therefore bone phosphate becomes an appropriate manure. So far 
we may reason generally, and upon just principles ; but the most refined experiments, and 
the utmost extent of discovery to which they have as yet led, tend only to the conviction, 
that we are only at the threshold of physiological science ; and that, if we hope to attain , 
exertions must be unremitted, and analyses of plants and earth be instituted with scrupulous 
exactitude. 
Bone phosphate was found to act unfavourably in heavy, binding soil ; it then was 
early discovered that 8 bushels of bone-dust, combined with an indefinite quantity of coal 
ashes (which latter lighten a soil most effectually), raised as good a crop as 16 bushels of 
bone-dust alone. But of late it has been found better to reduce bones to the state of 
superphosphate of lime, by treating them with one-half their weight of concentrated sul- 
phuric acid, diluted with twice its bulk of water — carefully adding, by degrees, the acid to 
the water, and not the water to the acid. This compound produces not only a biphosphate 
of lime, but also a considerable quantity of gypsum, in consequence of the union of sul- 
phuric acid with the carbonate of lime in the bones. It is altogether found to act more 
effectively in raising Turnips upon clay soil than the pure bone-dust. 
A great deal has been, and might be written on this subject ; but hypotheses are 
dangerous unless they go hand in hand with practical experiments. 
The other compounds of lime — as the muriate, nitrate, and sulphuret, do not claim 
particular notice. But I venture to suggest that a chloride of lime of full strength, 
mixed with about its weight of powdered alum, might be found not only to be a powerful 
disinfector, but also a very efficacious agent for the destruction of insects in the houses. 
Small quantities only should be tried, and the alum added gradatim, and not all at once. 
Chlorine is thus gradually, and for many hours, developed. If this hint be taken and 
acted on, we insist upon the greatest caution, and close observation. It may destroy 
the red spider at less risk than over-heated or ignited sulphur. 
