TIIE EXHIBITION 01' 1862. 
65 
a rich straw yellow. It is applied to fabrics with great readi- 
ness, requiring no mordant, and is one of the most permanent 
colours known. Carbazotic acid has other valuable properties ; 
for instance, it is a valuable medicinal agent, being similar in 
its action to quinine, only when administered it exerts its tinc- 
torial properties at the expense of the patient’s skin, dyeing 
him a lively yellow. It also has an intensely bitter taste, and 
for these reasons it has been suggested that arsenic and other 
poisons should be mixed with carbazotic acid. In cases of slow 
poisoning, the yellow appearance of the person to whom it was 
administered would at once give rise to a suspicion of some- 
thing- wrono-. 
It is a curious fact, that from coal-tar may be extracted 
the three primary colours, red, blue, and yellow, and these 
being obtained, every other tint is easily produced by their 
admixture. 
Our space forbids us even to refer to the other modes in 
which the former by-waste products in the manufacture of gas 
are utilized. We must now proceed to the next division of our 
subject — rags. We have spoken above of Baron Liebig’s pro- 
position to measure the civilisation of a country by the amount 
of soap which it consumes. We think a better standard of a 
nation’s progress would be the value which it attaches to rags, 
for, as Dr. Lyon Playfair observes, it is quite true that as 
nations rise high in the world they appreciate the value of rags 
more, and are willing to pay a higher price for them from 
other countries where their value is not appreciated. First and 
foremost of the many applications of this humble material is the 
manufacture of paper; for this purpose we buy from other nations 
no less than 15,000 tons of rags annually, besides using up four 
times that amount derived from the waste of our own population, 
representing a money value of rags equal to £700,000. Within 
the last ten years, paper has been manufactured from numerous 
other materials, but nothing has yet been found out which can 
in any way compete with rags in strength of texture or beauty 
of quality. The manufacture of paper scarcely comes within 
the limits of the present article, but we may refer to a very 
valuable improvement which has been effected within the last 
few years in connection with this product. Mr. Gaine described 
a process by which ordinary unsized paper could be converted 
into a material similar to parchment, by a momentary immer- 
sion in sulphuric acid of a certain strength, and more recently 
Messrs. De la Rue and Co. have taken up the manufacture of 
this parchment-paper commercially. The transformation effected 
is very striking. A sheet of common white blotting paper, 
which will scarcely bear its own weight when wetted, is con- 
verted in a few seconds into a substf nee possessing all the pro- 
VOL. ii. — xo. v. p 
