1924.} 
slightly soluble in water, which the first- 
mentioned of these gentlemen has denomi- 
nated. cafeine. 
Free or uncombined muriatic acid often 
evists in the hwman stomach, according toa 
late discovery of Dr. Prout; who, in one 
ease of a very deranged stomach, from 
which 20 ounces of a fluid was thrown off, 
separated therefrom above half a dra hm of 
muriatic acid, of specific gravity 1-160.— 
Brand’s Journal. 
The existence of two other spirituous 
fluids analogous to alcohol, as to forming 
ethers on combination with acids, have 
been ascertained by Messrs. Macaire and 
Marcet at Geneva: one of these, which 
they denominate pyrowylic spirit, was ob- 
tained during the rectification of pyrolignic 
acid, or the vinegar of wood; and the other 
of which; obtained from the same source, 
they call pyroacetic spirit, and have pretty 
fully described their properties in a paper 
read before the Society of Physics and Na- 
tural History in that city. 
Hydrogen gas is without smell, when pure. 
M. Berzelius has ascertained, that an 
odorous volatile oil is diffused in hydrogen 
gas, when prepared as usual from iron 
filings and diluted sulphuric acid; as may 
be rendered evident, by passing this gas 
through pure alcohol, by which, in a great 
measure, the smell of the hydrogen will be 
removed ; and if water be added to the 
alcohol which has been so treated, and it 
be set by in a flask for some days, a heavy 
odorous volatile oil will be found deposited 
therein. If an amalgam of potassium and 
mercury be put into pure distilled water, 
pure and inodorous hydrogen gas will be 
evolved. 
Electricity discriminated by its taste.—M. 
Berzelius has ascertained, that a current 
of positive electricity, passed by means of 
a metallic point on to the tongue, excites 
thereon an acid taste; but a similar cur- 
rent of negative electricity, a caustic and 
alkaline taste. 
Por comparing the illuminating power of 
gases made from coal and from oil.— Dr. A. 
Fye, of Edinburgh, has recommended the 
ascertainment of the proportion of olefiant 
gas in each of the several gases submitted 
for comparison, condensing the olefiant 
~ gas by means of chlorine gas, in the ab- 
sence of light; as otherwise, the carburetted- 
hydrogen gas would be in part condensed 
by the chlorine. Into a graduated tall glass 
jar, filled with water and inverted in a 
water-trough, introduce as much of the 
gas to be experimented upon, as will lower 
the water from 100 at the top, to the mark 
50 on the middle of the jar: a thick or 
black paper cover is then to be put on the 
jar, to exclude the light. Fifty measures 
of chlorine gas, previously prepared in a 
similarly graduated jar, are then to be 
passed up into the first jar, (which will 
lower the water to zero thereon), and the 
eame is then to be left for ten or fifteen 
Spirit of Philosophical Discovery. 
237 
minutes, in order for the olefiant and chlo- 
rine gases to combine, which is known to 
take place in equal quantities. On lifting 
up the paper cover, observe now the height 
of the water in the graduated jar, and the 
same will indicate the quantity of olefiant 
gas, in one-hundred parts of the gas expe- 
rimented upon. Suppose, for instance, the 
water should stand at 40, the gas under 
experiment must have contained 40 per 
cent. of olefiant-gas. On experimenting in 
this manner, repeatedly, on the coal and on 
the oil gas delivered to their customers in 
Edinburgh’ by the gas’ companies there, 
Dr. Fye found the proportion of olefiant 
gas in them to be, on the average, as 17 to 
31, or nearly as 1 to 1-8: from which, and , 
a variety of other experiments, the doctor 
is unwilling to allow the illuminating power 
of oil gas to be any more than double, bulk 
for bulk, that of coal gas, notwithstanding 
so many persons have contended for a 
triple illuminating effect in the former gas 
as compared with the latter. 
A source of danger from the use of culi- 
nary vessels of copper, has recently been dis- 
covered by Sir H. Davy, viz., that weak so- 
lutions of common salt, such as are daily 
made by adding a little salt to boiling vege- 
tables and other eatables in our kitchens, 
act strongly upon copper, although strong 
ones do not affect it. Sir Humphrey’s 
electrical conjectures, as to the cause of 
this peculiarity, appear to us rather far 
from satisfactory; but the fact is most im- 
portant to be generally known. 
The poisonous jfly-waters, which were a 
few years ago sold at the oil-shops, and 
were. much in use for clearing our dwellings 
of the swarms of common flies which in- 
fest them during the months of August. 
and September, have almost generally been 
laid aside, on account of the numerous loss 
of lives to children and to cats, &c. from the 
inadvertent drinking of these poisonous 
fluids. It is now, however, ascertained, 
that ground black pepper and moist sugar, 
intimately mixed in equal quantities, and 
diluted with milk, placed in saucers, adding 
fresh milk and stirring the mixture as often 
as necessary, succeeds admirably m occa- 
sioning the death of the flies, without being 
at the same time dangerous to the persons 
or useful animals which might unguardedly 
taste of this mixture. The chief breeding- 
places of these flies are the stables, and 
places wheré horse-dung is found. 
Why the eyes of a portrait, which look di- 
rectly ata spectator in front, do so ‘also in 
any other position, has remained without 
an explanation until lately. Dr. Wollaston, 
after considering the matter, observes, when 
two objects are seen on the ground at dif- 
ferent distances from us, in the same di- 
rection, one appears, and must be repre- 
sented ina picture, as exactly above the 
other, so that a vertical plane from the 
eye would pass through them; and since 
such line will be seen upright, however far 
we 
