88 
REPORT ON THE INDUSTRY OE MANURES 
Mr. Lawes has favoured the Reporter with the following interesting particulars as to 
the most recent and improved mode of manufacturing superphosphate, its average com¬ 
position, and its present market price:— 
“ The phosphatic materials are first ground to a very fine powder by mill-stones ; the 
powder is then carried up by means of elevators, and discharged continuously into a long 
iron cyliuder, having agitators revolving within it with great velocity. A constant 
stream of sulphuric acid, of sp. gr. 1-66, enters the cylinder at the same end as the dry 
powder, and the mixture flows out at the other end in the form of a thick mud, having 
taken three to five minutes in passing through the machine. The quantity turned out by 
such a mixing-machine is about 100 tons daily. The semi-fluid mass runs into covered 
pits 10 to 12 feet deep, each of sufficient size to hold the produce of the day’s work. It 
becomes tolerably solid in a few hours, but retains a high temperature for weeks, and 
even months, if left undisturbed. 
“ The composition of a superphosphate of good quality, made partly from mineral 
phosphate and partly from ordinary bones, may be stated as follows :— 
Soluble phosphate . 22 to 25 
Insoluble phosphate . 8 „ 10 
Water . 10 „ 12 
Sulphate of lime. 35 „ 45 
Organic matter . 12 „ 15 
Nitrogen 0-75 to 1*5 per cent. 
per cent. 
?? 
55 
“ If sufficient sulphuric acid were used to decompose the whole of the phosphate of 
lime, the product would be too wet to be packed in bags, and would require either to be 
mixed with extraneous substances of a dry and porous nature, or to be artificially dried. 
“ The price of the best descriptions of superphosphate ranges from £5. 15s. to £6. 10s. 
per ton, and of that made from purely mineral phosphate from £4 to £5. 5s. per ton.” 
Of the raw materials annually worked up into superphosphate in Great Britain, Mr. 
Lawes estimates that about half is derived from the deposits of fossil bone-earth, or co- 
prolite, discovered of late years in several parts of England. Bone-ash, chiefly imported 
from South America, animal charcoal from Germany, and bones from all parts of the 
world, together supply about forty per cent, more of the raw material; while the remain¬ 
ing ten per cent, of the total supply is made up by guano (chiefly of the less nitrogenous 
and more phosphatic kinds) wish a little apatite (say 200 to 500 tons per annum) ob¬ 
tained from Spain, Norway, and America. 
Importation of Manures into Great Britain .—These data alone might serve to indicate 
that the industry of manures, since the impulse it received in 1840, has afforded occupation 
not only to the inventive and manufacturing, but also to the commercial activity of the 
English nation. But of this the origin and development of the guano trade affords 
direct evidence, 
The British guano trade can scarcely be said to have existed, as a regular branch of 
commerce, before Liebig drew attention to the subject. Its principal importers, Messrs. 
Gibbs and Sons, only began their trade in 1842, two years subsequently to the appear¬ 
ance of Liebig’s work, which dwelt strongly on the value of this deposit. In 1841 
guano had already been tried on sixty English farms, as appears from a report published 
in that year by the Council of the Royal Agricultural Society. A few such trials had, 
in all probability, been made in the two or three preceding years ; seeing that several 
cargoes of guano were imported and sold (at upwards of £20 per ton) by a Mr. Myers, 
before Messrs. Gibbs engaged in the business. The statistics, of the entire guano trade 
are not before the Reporter; but of its development during the last twenty years some 
idea may be formed from the experience of Messrs. Gibbs and Sons. That eminent firm 
in the first year of their trade (1842) only imported 182 tons of guano ; in 1843 their 
importations had already reached 46(17 tons ; and in 18G2, the twentieth year after their 
commencement, tlieir total supplies (as well for foreign as for British consumption) had 
attained to the enormous rate of 435,000 tons per annum. Of that vast total, from a 
fourth to a third was retained for use in the United Kingdom. It may interest agricul¬ 
tural readers to know that at the outset of the regular guano trade the price ranged be¬ 
tween £10 and £15 per ton; that during the two years, 1846-48, it remained at £9, its 
lowest point; that during the next four years 1849-53, it advanced but slightly, to £9. 
