On Indigogene. _ 415 
apartment and the currents of cold air from the chimney acting 
on the surface of the body, and in the cases of rheumatism, more 
particularly, defeating the object for which the warm-bath was 
_ prescribed, 
When walking over the building, we had an opportunity of 
examining a model of a chemical apparatus for producing chaly- 
beate water, by Galvanic action; but as we were informed, con- 
siderable improvements were making on the larger apparatus, 
we will take an early opportunity of laying-a description of it 
before our readers. 
The last and not the least improvement in this establishment 
is the very moderate sum which is intended to be charged for each 
bath. Those who have been accustomed to frequent Brighton 
for cheapness, will now here be agreeably surprised at finding 
infinitely superior accommodation for the same money. 
LXXXVI. On Indigogenc. By J. Murray, Esq. 
To Mr. Tilloch. 
Sir,— I BEG to submit some remarks on the substance called 
by Brugnatelli indigegene. 
It is obtained from indigo, a substance one of the products of 
the Indigofera and Isatis, and the varied species of which are 
natives of the East Indies, Cape of Good Hope, and New Hol- 
land. The extract from the letter of M. Van Mons of Brussels, 
in the Philosophical Magazine, first called my attention towards 
this curious body. 
If indigo in the form of powder be projected on a red hot 
iron, a vapour of a blueish colour arises, and a red shade passes 
over the surface of the iron. This vapour exhales a peculiar 
odour somewhat resembling burnt malt; and when condensed, 
the indigogene is evolved under the form of fine needlelike cry- 
stals of a copper colour and histre: viewed through a lens, some- 
times arborescent groups appear. The mode which I adopt for 
procuring the indiyogene is as follows: 
A small glass capsule (a watch glass will suit) containing the 
powdered indigo is set in one of the sliding rings of the stand 
usually accompanying an Argand’s lamp. A flat piece of glass is 
placed on the capsule, and it is then submitted to the action of 
heat. Water is first given off, then succeeds a reddish vapour, 
which attaches to the flat piece of glass (from which it is diffi- 
_eultly removed by spirits of turpentine); and ultimately, after the 
heat has been considerably inereased, the substance in question 
mt is 
* 
