1833.] Miscellaneous. 495 
to gas illumination, and the eyes of such persons must therefore serve an appren- 
ticeship before they learn to see objects in their true colours. 
The blue colour of gas-light was ascribed to the badness of the gas; and the 
apparent removal of this injurious quality has been attributed to its increased purity 
and to improved methods of burning it: but the truth is, that bad gas, or an 
imperfect combustion of good gas, produces a much redder light than good gas 
burnt in the best manner. The smoke which is produced in the former cases 
invariably reddens the flame, and its perfect removal causes the gas to approximate 
to the light of the sun, which is always bluer than that of the whitest flames from 
wax, oil, or tallow. 
There is a very pretty experiment illustrative of some of the preceding observa- 
tions, which is easily made. Place two candles at the distance of two or three feet 
from the eye, and about one foot from each other, and having closed oneeye, fix the 
other intently upon either of the candles, as if it were examining with attention 
some point of the wick. The other candle will be seen by indirect vision, and after 
a little time, it becomes much brighter and bluer than the first, in consequence of 
the part of the retina on which its light falls being more susceptible than the more 
frequently used portion in the axis of the eye, upon which the light of the second 
is incident. The higher degree of excitation of the retina, produced by the candle 
seen indirectly, renders that portion of the membrane less sensible to the red rays ; 
and if the excitation is continued, the image will become actually blue, and will be 
surrounded with a halo of yellow nebulous light. The blue image, indeed, will 
sometimes disappear, and leave nothing in its place but a nebulous hole.—PAz}. 
Mag. March, 1833. 
3.—Substances contained in Opium 
M. PELLETIER in an elaborate memoir on opium printed in the Annales de Chimie, 
mentions the following principles as contained in opium ; viz. narcotine, mor- 
phia, meconic acid, meconine, narceine, caoutchouc, gum, bassorine, lignine, resin, 
brown acid, and extractive matter, fixed oil, and a volatile, but non-oleaginous prin - 
ciple, which rises in distillation with water. 
Added to these substances, M. Berrr announces (Journal de Pharmacie, April, 
1832), another peculiar principle ; it is bitter, crystallizable, forms salt with acids, 
especially with acetic acid, with which it gives crystals in the form of very white 
scales, and with sulphuric acid, white silky crystals ; no name is given to this sub- 
stance by its discoverer. 
M. RosiqueEt, it also appears, has separated a new alkali from opium, which he 
calls paverin. Only a few details of its properties are yet given (Journal de Pharm. 
Noy. 1832). It ditfers very remarkably from other vegeto-alkalies in being soluble 
in water ; saturates acids, is insoluble in potash, and contains much azote; it 
is very poisonous, and acts very particularly on the spinal marrow.— Phil. Mag. 
4.—Death of Captain J. D. Herbert. 
It is with feelings of sincere grief that we record the loss of our most worthy 
friend and late coadjutor, Captain J. D. HErBert, at Lukhnow on the 24th instant. 
He had been for some time suffering under the effects of the climate: a sudden 
determination of blood to the head was the immediate cause of the fatal event. 
