December 2,1871.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
457 
hatching season of the animal, and expose them to the 
sun to kill the insect. These gum-lac twigs are sold 
"under the name of stick-lac. Those of Siam are con¬ 
sidered the best, those of Assam next, and those from 
Bengal the worst. 
There arc three kinds of lac in commerce—stick-lac, 
which has just been described, seed-lac and shell-lac. 
The resinous concretion is taken from the twigs, coarsely 
powdered, and triturated with water in a mortar. The 
greater part of the colouring principle is thus dissolved. 
The granular portion which remains is dried in the 
sun, and constitutes seed-lac. Shell-lac is obtained by 
melting seed-lac and straining whilst hot. It is then 
dropped upon smooth stems of the banyan tree, and so 
runs into thin plates, which are known in commerce 
under the name of shell-lac. 
These three lacs have the following composition:— 
Stick-lac. 
Seed-lac. 
j Shell-lac. 
Resin'*. 
68-0 
88"5 
90-9 
Colouring matter . . . 
10-0 
2-5 
'5 
Wax. 
60 
4 - 5 
4-0 
Gluten. 
5 5 
20 
2-8 
Foreign matters . . . 
6-5 
Loss . . . . • . . . 
4"0 
2-5 
i-8 
100-0 
100-0 
100"0 
The colouring matter of the insect is identical with 
that of cochineal and kermes, and it has been employod 
as a scarlet dye-stuff in the East from time imme¬ 
morial. 
Lac-lake and lac-clye are preparations imported into 
this country from India since 1796. They are both pre¬ 
pared by acting on stick-lac by a weak alkaline solution, 
to which is then added a solution of alum. This pro¬ 
duces a precipitate, which, when washed and dried, is 
ready for use. Although both these lakes are prepared 
with the same substances, lac-dye is considered much 
superior in quality. This is due to the greater care be¬ 
stowed on its preparation. The details of the process 
are kept secret. 
To dye woollen cloths with them, they arc dissolved 
in a weak solution of vitriol, to which is added a little 
oxymuriate of tin, and the cloth dipped in when the 
liquid is near the boil. It only requires washing and 
finishing to be ready for market. 
Some years ago, Messrs. E. Brooke and Co., of Man¬ 
chester, introduced a lac-dye much superior to that 
imported from India, which they prepare bv treating 
stick-lac with weak ammonia, and adding chloride of 
tin to this solution, when a fine red precipitate is formed, 
which, collected, is ready for use. 
Murexide or Homan Purple. —Although this colour has 
now been superseded by those derived from coal-tar, I 
call your attention to it as an example of the assistance 
rendered by the progress of chemistry to the art of 
calico-printing. 
In 1776, the illustrious Swedish chemist, Scheele, dis¬ 
covered uric acid in human urine. In 1817, Brugnatelli 
found that nitric acid transformed uric acid into a sub¬ 
stance which he called erythric acid , but which was 
afterwards named by Wohler and Liebig alloxan. In 
1818, Dr. Profit found that this latter substance gave, 
when in contact with ammonia, a beautiful purple-red 
colour, "which he named par pur ate of ammonia —the pro¬ 
duct known by the name of murexide since the researches 
of Liebig and Wohler in 1857. These discoveries re¬ 
mained dormant in the field of pure science until the 
year 1851, when Dr. Saac observed that when alloxan 
came in contact with the hand it tinged it red. From 
this he inferred that it might be employed to dye 
woollen fabrics red, and further experiments showed 
that if woollen cloth, prepared with a salt of tin, were 
passed through a solution of alloxan, and then submitted 
to a gentle heat, a most beautiful and delicate pink 
colour was obtained. 
In 1856, MM. Depouilly, Lauth, Mcistcr, Peterson, 
and A. bchlumberger, applied it as a dyeing material 
to silk and wool, and succeeded in producing red and 
purple colours, by mixing the murexide with corrosive 
sublimate, acetate of soda and acetic acid. 
For printing upon cotton, a mixture of murexide with 
nitrate of lead or acetate of zinc, properly thickened, 
was printed on the fabric, which was then allowed to 
dry for a day or two, when the colour was fixed by 
passing them through a mixture of corrosive sublimate, 
acetate of soda and acetic acid. 
The uric acid required for the preparation of such 
large quantities of murexide, was obtained from Peru¬ 
vian guano. The guano was treated with hydrochloric 
acid and washed. The insoluble mass was then treated 
with nitric acid of specific gravity P40. When the 
action of the acid was completed, the mass was treated 
with warm water to dissolve out the alloxan. It was 
j then carefully evaporated to such a degree that it be¬ 
came solid on cooling. The solid mass had a brown or 
violet colour. 
|).idiimwnt;trjr anir fab fnrmtogs. 
PROSECUTION OF A CHEMIST FOR MISREPRESENTATION. 
At the Leicester Town Hall, on Monday, 20th Novem¬ 
ber, William Lakin was charged with wrongly repre¬ 
senting himself as a doctor of medicine. 
Mr. Owston for the proscction, Mr. Fowler for the 
defence. 
Mr. Owston pointed out that under the Medical Act 
it became necessary that any one practising in medicine 
should be entered in the Medical Register, and the absence 
of any name from that Register was sufficient ground for 
supposing that he was not an enrolled member of that 
Society, and was not entitled to style himself doctor of 
medicine, and had contravened the Act. He then de¬ 
scribed defendant’s shop, which, he said, contained 
all the concomitants of an apothecary’s shop, and upon 
the door-plate was “ Dr. Lakin.” He also pointed out 
that defendant had issued a certificate, in which he had 
signed himself “William Lakin, M.D. (U.S.).” 
William Dalrymple, manager of the Leicester Pro¬ 
vident Dispensary, who said he laid the information 
in this case. Defendant resided at 16, New Bond 
Street. Witness had been in the habit, almost daily up 
to Nov. 13, of passing his house. He had noticed on a 
brass plate, at the right-hand side of the door, at 16, 
New Bond Street, “Dr. Lakin.” Had noticed in the 
window three or four bottles containing coloured liquid, 
castor oil (the bottles having on them the Latin names), 
syringes, catheters, pamphlets on medical subjects. 
Through the door he could see into the shop, and in it 
were the ordinary fittings of a surgeon’s shop. Over the 
window and door was a board, containing “Dr. Lakin, 
botanic practitioner.” 
By Mr. Fowler: As an outside observer it did not strike 
him as the shop of a chemist and druggist, by the entire 
absence of scents and other drugs. The books on medi¬ 
cine are not usually exhibited in the shop of an ordinary 
chemist and druggist. In the ordinary druggist’s shop 
the window was made attractive; defendant’s was left 
careless, as is usual in open surgeries. Open surgeries are 
not customary in Leicester, but are in London and other 
large towns. Was not aware that Sir. Lakin was 
registered as a chemist. 
Re-examined: Did not usually find a plate at the 
entrance of a druggist’s shop. 
Charles H. Marriott said he was M.D. and F.R.C.S. 
The title of M.D. was conferred by various universities 
throughout the world. The only universities in England 
that could grant that degree were Oxford, Cambridge, 
