THE EXHIBITION OF 1862. 
67 
desideratum is accomplished. He takes the mixed fabric 
and subjects the rags to the action of steam at a pressure of 
four or five atmospheres. The effect of this is to char the 
wool, rendering it very friable, whilst the cotton is not in 
the least injured. The action over, the rags are beaten and 
sifted, when the cotton is left behind in the fibrous state, 
whilst the brittle matter into which the wool has been con- 
verted separates in the form of powder. The cotton, being as 
firm and as strong as ever, may be apphed to a variety of 
purposes : some very excellent paper made of cotton separated 
in this manner is shown by Mr. Ward ; the wool is sold as a 
manure, under the name of “ crenate of ammonia/'’ 
But woollen refuse can be apphed to higher purposes than 
forcing early cabbages ; the chemical manufacturer, utilizing in 
another way the nitrogen which it contains so plentifully, 
throws it into his cauldron, and stews it down with 
pearlash, horns and hoofs of cattle, old iron-hoops, blood, 
clippings of leather, and broken horse-shoes — when it 
produces the beautiful yellow and red salts, known as the 
prussiates of potash, magnificent crystals of which may be seen 
in the Eastern Annexe. From these salts, the rich and valuable 
pigment, Prussian blue, is made ; and under this form our old 
rags start upon a fresh career of beauty and usefulness, forming- 
in their turn other waste products which are again seized hold 
of by skilful intelligence, and re-utilized. 
We now approach the vast and important subject of Bones. 
The uses to which these are apphed are endless. Their 
mechanical applications for knife-handles and similar purposes 
do not require, more than a passing reference here, but we may 
state that the quantity annually imported into this country 
represents a money value of £400,000. Chemically speaking, 
bone consists of a little more than half its weight of phosphate of 
lime, and about a third of its weight of cartilage, the remainder 
being made up of earthy matters unimportant for our purpose. 
The applications of each of these constituents of bone are 
numerous : the cartilage is capable of being extracted by 
boiling water under pressure, being converted into a gelatinous 
substance, and is then used in large quantities by the calico- 
printer for stiffening the fabric. The substances known to 
housekeepers as gelatin and calfs-foot jelly usually consist of 
this extracted cartilage in a purified form. Isinglass is quite a 
different substance in its origin, although, chemically speaking, 
only gelatin. It is prepared from the sounds of certain species 
of sturgeon; and, from its somewhat high price, has long- 
tempted manufacturers to produce an imitation in ordinary 
gelatin. The success which has attended this endeavour may 
be seen by an examination of several cases in the Eastern 
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