484 
CARBOLIC OR PHENIC ACID AND ITS PROPERTIES. 
hibition, in M. Casthelaz’s case, a coloured material, known in the trade by the name of 
soluble garnet, which, I am informed, is used especially by M. Chalamel, of Puteaux - 
this substance is particularly remarkable, as it is isomeric with th e pur pur ate of ammonia, 
or murexide. Although the preparation of this colouring material was first pointed out 
by M. Carey, still it is really due to a previous discovery, by Hlasiwitz, who called atten¬ 
tion to the reaction of cyanide of potassium upon picric acid, and to which chemical re¬ 
action we owe the knowledge of manufacturing the isopurpurate for industrial purposes. 
Before taking leave of picric acid, it may not be without interest that I should state a 
curious application which has been made of the explosive property of its salts. During 
these last few years the picrate of potassium has been employed in great quantities, by 
Mr. J. Whitworth, for charging the bombs for destroying the iron plating of ships. 
When the projectiles thus prepared strike the iron masses, the enormous propelling force 
with which they are expelled from the gun is instantaneously converted into heat, and 
to such an extent that the ball becomes red hot, the heat decomposes the picrate of 
potash, and a violent explosion ensues, owing to the enormous quantities of vapours 
and gases which are generated in an instant of time. Whilst the alkaline picrates are 
endowed with such formidable properties, they also possess properties which are useful 
for the alleviation of human misery. Picric acid is an efficacious remedy in intermittent 
fevers. Persons affected with such types of fever, upon whom quinine has lost all its 
beneficial effects by continuous usage of it—and this is the case with some of our soldiers 
who return from India—derive, I am glad to say, wonderful benefit from the use of 
picric acid and picrates, as Dr. Aspland has proved to be the case, at the military hospital 
at Dukinfield. The knowledge of this fact may be useful in districts in which exist poor 
populations, for it affords them a cheap febrifuge ; and, moreover, picric acid is not 
dangerous, as arsenical preparations are, nor does it derange the stomach like quinine. 
To return to the colours derived from carbolic acid, allow me to remind you that when, 
in 1834, Runge discovered that acid amongst the products of coal tar, he observed at the 
same time the existence of two colouring substances, to which he gave the name of 
rosolic acid and brunolic acid. 
I will not detail here the processes by which Runge extracted these substances from 
the residue of coal tar by means of lime, nor the method adopted by Messrs. Smith, 
Dussart, and Jourdin for producing these substances by direct oxidation of phenic or 
carbolic acid, but will describe rapidly the process which we now use to manufacture 
rosolic acid, and which should not be attributed, as is generally believed, to M. Kolbe, as 
it is due to M. Jules Persoz, the son of the celebrated professor of tinctorial chemistry in 
the Conservatoire des Arts et Metiers. His process consists in making oxalic acid act 
upon sulphophenic acid at a temperature of about 160 degrees, and the product which 
results from it has the bronze green appearance of cantharides. To render it suitable 
for employment in dyeing it is only necessary to wash it so as to separate from it all the 
sulphuric acid with which it is contaminated. It is then known under the name of 
yellow coralline or aurine. It was our firm who first, in 1863, discovered that rosolic 
acid thus prepared could be employed directly as a dye, and introduced it to dyers under 
the name of aurine. This substance gives to silk and albumenized cotton magnificent 
orange colours, like those of basic chromate of lead or of turmeric. In 1860, M. Persoz, 
junior, discovered also that if rosolic acid was heated under pressure with ammonia it 
gave rise to a red substance, which he called peonine. Messrs. Guinon, Marnas, and 
Bonnet perfected the manufacture of peonine, and gave it the name of red coralline. 
This colouring substance gives to silk and "worsted a flame-coloured tint and very bril¬ 
liant scarlets. This firm were also the first to produce and introduce, towards the end of 
1860, a blue dye, derived from carbolic acid, or, more so, rosolic acid, which they called 
azuline. Azuline is obtained by heating for several hours, at the temperature of about 
180 degrees, a mixture of rosolic acid and aniline. It is only necessary then to treat this 
product with sulphuric acid, and to wash it with benzine, to produce a beautiful blue 
colouring matter, which presents, when dry, a red mass with gold-coloured tints. Azu¬ 
line. although discovered before the aniline blues, which have since become formidable 
rivals to it, is still, I may add, manufactured in competition with them. 
To Messrs. Guinon, Marnas, and Bonnet is also due the first production of a green 
derived from coal-tar products. It was manufactured in 1863, therefore some months- 
before the appearance of an aniline green, known as vert d'Uzebe , which, however, with 
the exception of the iodine greens, is the only one now employed in dyeing. Viridine 
was obtained by this firm from a mixture of aniline, benzoic, and rosolic acids. 
