CHEMISTRY. 
368 
and they all agree with refpeff to its antifeptic virtue. 
But the experiments of Macquart and Vauquelin prove, 
that this antiputrid quality does not belong to the gaftric 
juice of ruminating animals. Some 'chemifts think that 
the gaftric juice ails upon food rather as a decompofing 
principle, than as a folvent: but, indeed, its powers are 
known with as little precifion as its chemical compofition. 
It appears from the curious experiments of Mr. Smith, 
that the fub.cutaneous parts of living animals, when 
wounded, or llimulated, pour out a lecretion analogous 
to the gaftric liquors in the property of coagulating milk, 
and in adding as a decompofing principle on animal and 
vegetable fubftances. 
Of the HUMOURS, or ANIMAL MATTERS, not 
yet examined; such as SWEAT, the NASAL 
MUCUS, CERUMEN,TEARS,GUM of the EYES, 
SEMINAL FLUID, and EXCREMENTS. 
There are many animal fluids and matters, which have 
not yet been examined. It is therefore not fo much with 
a view to exhibit their properties, as to engage young 
phylicians to make refearches, equally new and ufeful, 
that we propofe to fpeak curforily refpefting the humour 
of tranfpiration, of fweat, of the mucus of the noftrils, 
the cerumen of the ears, the tears, the gummy matter 
of the eyes, the feminal fluid, and the excrements. 
Phylicians have difcovered a great analogy between the 
fluid emitted by cutaneous tranfpiration, and urine; 
they have obferved, that thefe excretions mutually anfwer 
the liune purpofe in many circumftances, and are there¬ 
fore naturally led to confider the vaporous fluid of tranf¬ 
piration as of the fame nature as urine. Medical prac¬ 
tice has Ihown, that its qualities are fubjedt to variation; 
that its fmell is faint, aromatic, alkaline, or four; that 
its confiftence is fometimes glutinous, thick, tenacious, 
and that it leaves a reftdue on the Ikin; that it often 
tinges linen with various fliades of yellow. Berthollet 
affirms, that fweat reddens blue paper; and that this 
phenomenon takes place more particularly in parts effeft- 
ed with the gout. He thinks it contains the phofphoric 
acid. It has been hitherto impoffible to collect a l'uffici- 
ently large quantity of this excrementitial humour, to 
examine its properties with accuracy. Many inquiries, 
therefore, remain to be made, which can only be under¬ 
taken and purfued by phylicians in peculiar circumftances 
and occafions. 
The humour, prepared by the membrane of Schneider, 
which is thrown out of the noftrils by fneezing, deferves 
to be carefully attended to by phyflcians. It is a kind of 
thick mu'cilage, white or coloured, more or lefs fluid, or 
conliftent in certain affedlions, and more efpecially in 
catarrhs. It appears to be a mucus and alkaline fub- 
'ftance, which becomes thick, in confequence of abforb- 
ing oxygen from the atmofphere. 
The yellow, greenilh, or brown matter, which is col¬ 
lected, and becomes thick, in the auditory canal, and is 
known by the name of cerumen , becaufe of its confiftence, 
has not been fufflciently examined. It is very bitter, 
and appears to be of a refinous nature-; it fometimes be¬ 
comes to concrete, as to flop the auditory canal, and pre¬ 
vent the free paffage of found : there leems to be lome 
analogy between this and the inflammable matter of the 
bile. Cerumen is a compound fubftance, confifting of a 
number of wliitilh particles, connefted together by a te¬ 
nacious matter, which is foiuble in warm water. Ceru¬ 
men differs from bile in being infoluble in alcohol, and 
not being decompofed by diluted acids. 
We are better acquainted with the nature of the tears, 
which are prepared in a peculiar gland, fituated towards 
the external angle of the orbit, and deftined by nature 
to maintain the humidity and liipplenefs of the external 
parts of the eye. This fluid is clear, limpid, and manifeftly 
fait; it fometimes ifiues out of the eye in large quantities. 
In the natural ftate, it gradually flows into the noftrils, 
and appears to dilute the mucus. Moft authors who have 
fpoken of this liquor, and in particular Pierre Petit, a 
phyiician of Paris, who publifhed a treatife on Tears 
about the end of the laft century, confider them as water 
nearly pure. We have found them to contain a peculiar 
mucilage, which becomes thick by abforbing oxygen, 
muriat of foda, and foda, in a cauftic ftate; after that, 
the humour of the tears is limilar to the mucus of the 
nofe with which it mixes. 
Neither has the chemical nature of the feminal humour 
been much more inquired into than that of the forego¬ 
ing matter.—The few obfervations, which it has been 
hitherto poflible to make on this liquor, have Ihown, that 
it refembles animal mucilages, becomes fluid by cold and 
by heat, and that the aCtion of fire reduces it to a dry 
and friable fubftance. 
The anatomical and microfcopical obfervations on this 
fubjeft have been carried much further. They have 
Ihown, that the feminal humour is an ocean, in which 
certain fmall round bodies fwim, which poflefs a rapid 
motion, and are by fome confidered as living animals, 
deftined to reproduce the fpecies, and by others as orga- 
nicmoleculse,adaptedtoforma livingby being theirunion. 
The microfcope, in the hands of a modern oblerver, has 
likewife Ihown cryftals formed in the leminal liquor by 
evaporation and cooling. Itmuftbe admitted, however, 
that thefe fine experiments have not hitherto been at¬ 
tended with confequences which have advanced the fci- 
ences, but that they have merely afforded data for the 
conftru&ion of certain ingenious hypothefes. See under 
Animalcule, in vol. i. p.727, of this Encyclopaedia. 
Vauquelin has publilhed, in the Annales de Cbimie , 
(April 1791) a memoir on the Human Semen. The fol¬ 
lowing are the only new faCts which it contains : 1. This 
fubftance has a faint fmell, a (harp and flightly aftringent 
tafte, its weight is greater than that of water. 
2. To afcertain whether the air be the caufe of the li¬ 
quefaction, which this humour undergoes fome minutes 
after it has been emitted, he expofed equal quantities of 
it in the air, and in clofe veffels containing no air. The 
liquefaction having taken place in the fame manner, and 
in the fame time, he concluded, that neither the air, nor 
the fubftances diffolved in it, produced this effeCt. 
3. By leaving the feminal liquor to liquefy in a finall 
glafs ball, terminated by a very narrow tube, its volume 
was not increafed. This was eafily obferved, by marking 
the place to which the liquor role. He l'eems to doubt 
whether this effeCt is to be afcribed to caloric. 
4. When the lemen is kept for fome days expofed to 
the air, in a fmall caplule, long tranfparent cryftals are 
depofited in it, of the fhape of a priftn with four fides, 
terminated by pyramids with four faces. According to 
the experiments of this author, thefe cryftals, which had 
been announced in the Journal de Phyfique, are very pure 
phofphat of lime. 
5. Avery white pellicle, forming on the feminal liquor, 
fome time after it has been expoled to the air, which is 
fet with opaque white points. Thefe points are of the 
fame nature with the fucceeding cryftals, and differs from 
them only in not being tranfparent. 
6. If the air in which the feminal matter is expofed be 
humid, it does not dry completely, but remains loft and 
ductile. Before arriving at this ftate, it undergoes many 
changes, which Vauquelin has carefully deicribed. At 
firft, it affumes a yellow colour, and then becomes acid: 
Byfi grow on its furlace, cryftals are depofited in it, and 
at lalt it exhales the odour of putrid fifti. If, on the con¬ 
trary, the air be dry and warm, the femen dries, fpeedily 
becomes dry and brittle, like horn; it loles, during the 
deficcation, about nine-tenths of its weight 
7. The feminal liquor exhibits a very marked alkaline 
character, which is owing to the foda the author dif¬ 
covered in it. 
8. Water, at whatever temperature it may be, from 
zero to the boiling point, does not diffolve femen that 
has not been previoufly liquefied ; but it combines with 
the 
