i 882 .i 
Safety Rejected. 
479 
of cotton-waste, &c., are perfectly familiar, and the rise in 
temperature in beer-worts and wine-must during fermenta- 
tion is fully known. But the heat thus produced is no more 
obtained for nothing than is the heat of a furnace. The 
process that takes place in such heaps of wet vegetable 
matter is slow combustion ; the carbon and hydrogen of the 
hay, &c., combine with oxygen to form carbonic acid and 
watery vapour, and the heat generated is in proportion to the 
quantity of matter destroyed. It may therefore be said that 
Mr. Neison dries one part of a stack of hay with the heat 
generated by burning another portion. Now not only men 
of Science, but manufacturers of all classes are of opinion 
that heat may be obtained more cheaply by burning coal than 
by burning hay or straw. Were it otherwise we should find 
them buying hay for fuel ! 
But the case is really worse than if a certain portion of 
the hay had been taken and burnt in a furnace, in order to 
dry the rest by means of the heat thus produced. Hay is a 
complex material, and if it is allowed to ferment — or, in 
other words, partially to rot — some of its constituents are 
destroyed more readily than others. The woody fibre, or 
cellulose, which forms, so to speak, the skeleton or frame- 
work of the stalks and leaves of the grass, is scarcely attacked 
at all. But this cellulose is precisely the least valuable part 
of grass or hay for the food of cattle. It is but very spar- 
ingly digestible, so that the greater part of the dung of cows. 
&c., is composed of cellulose, ground up into a fine fibrous 
pulp, but not dissolved. 
On the other hand, the sugary matter naturally present in 
grass, which renders the hay agreeable to the taste of cattle, 
and which has a considerable nutritive value, is the first in- 
gredient to be destroyed in fermentation. Its oxidation or 
combustion — for the two words are in such cases practically 
convertible — is the source of the heat which in the Neison 
process is to volatilise the moisture present and dry the hay. 
After the sugar the starchy matter, the albumenoids, and, in 
short, all the valuable constituents are successively destroyed, 
and there remains, if the fermentation is only allowed to go 
on long enough, the woody fibre above mentioned. Instead, 
therefore-, of utilising this heat of fermentation for drying 
vegetable matters, it should be rendered impossible by at 
once depriving them of moisture. This is done by Nature 
when hay is made in dry, sunny weather, with a gentle wind. 
Such hay retains its colour, its odour, its taste, and its 
chemical composition, and is, in faCt, grass deprived of the 
greater part of its natural moisture. The same end is 
