482 
The secretion of the Schneiderian membrane, 
according to the analysis of Berzelius, is com- 
sed as follows :— 
UCUS sesecsicces 5.33 
Alcoholic extractive and alkaline lactate 0.30 
Chlorides of potassium and sodium 0.56 
Aqueous extractive, traces of albumen, 
and a phosphate ........ses2e050. 0.35 
combined with the mucus...... 0.09 
Water ee ee eee eee teat eereerreeeeee 93.37 
100,00 
The chemical characters of the substance 
which Berzelius notices in this analysis as 
“mucus” are as follows. It is not soluble 
in water, but swells up and becomes transpa- 
rent. When dried it 1s again capable of being 
swelled by water; but after this experiment 
has been repeated several times it becomes 
of a yellow colour, and assumes somewhat 
the appearance of pus. When boiled in water 
it neither hardens nor contracts ; but after this 
treatment it is found, to a certain extent, to 
have lost its property of swelling. When dry 
it is of a yellow colour and transparent. By 
distillation it yields carbonate of ammonia and 
empyreumatic animal oil. ‘The ashes obtained 
from this substance yield phosphate and car- 
bonate of lime, with traces of carbonate of 
soda. This mucus is soluble in weak sulphuric 
acid ; the strong acid darkens its colour and even- 
tua!ly destroys its texture. Weak nitric acid co- 
agulates it superficially and renders it partially 
yellow: long digestion in this acid causes 
its solution. Acetic acid contracts it, but 
does not dissolve it even when assisted by 
heat. It dissolves from it, however, a portion 
of albumen, which renders the solution preci- 
pitable by the ferrocyanuret of potassium. 
Caustic potash renders this mucus more tena- 
cious, but by digestion it dissolves it. In- 
fusion of galls coagulates it when dissolved 
in acids or when swelled by water. These 
characters described by Berzelius may be re- 
ceived as the genera! properties of that substance 
to which mucous secretions owe their viscous 
character. 
Urinary mucus.—This form of mucus is 
best obtained by allowing recently voided urine 
to remain at rest in a tall glass vessel, when 
the mucus will subside after some hours, and 
may be collected by pouring off the super- 
natant fluid as nearly as possible without 
disturbing the precipitate, and throwing the 
remaining part of the secretion on a filter; 
the mucus will now be retained on the paper. 
Its properties are as follows :—when ined cn 
paper it exhibits a bright surface; on being 
moistened, however, it rapidly assumes its 
original appearance. It is insoluble in sul- 
phurie acid, but the nitric and acetic acids 
dissolve it in large proportion, and the solution 
is precipitable by ferrocyanuret of potassa: 
caustic potassa in solution dissolves it entirely. 
Sualivury mucus.—The saliva, as it passes 
from the mouth, contains, in all probability, 
two kinds of mucus; one derived from the 
pueous membrane lining the mouth, and the 
MUCUS. 
other from the internal membrane of the salivary 
ducts. When saliva is allowed to stan 
very soon separates into two parts; one @ 
supernatant liquor of a slightly milky hue, 
and the other a deposit of a white colour, 
which in this state does not exhibit the ordinary 
physical characteristics of mucus. On pouring 
off the liquor, however, and then agitating the 
deposit with water, it immediately assume 
the glairy character; indeed, without the addi. 
tion of water it will exhibit a mucoid tenacity 
if an attempt be made to raise it from the 
vessel in which it has collected. The liquo 
which has been poured off from this dens 
form of the principle still contains a portior 
of mucus in suspension, which may be 
tained by dilution with water, and may pre 
bably be a less coherent form of mucus secreted 
by the lining membrane of the salivary duets 
These two forms of mucus have much the 
same chemical characters, being insoluble iz 
water and coagulable, and rendered firme 
by the acetic, hydrochloric, and sulphuri 
acids. The liquors obtained by digesti nes 
acids on mucus are not precipitable = t 
addition of alkalies, which shows that th 
form of the secretion does not contain any 
free subphosphate of lime. It is dissolve 
by caustic alkalies and peels by th 
acids when thus dissolved: the solution it 
alkalies, however, is not Coney a residue 
being always obtained, which is soluble ia 
acid, but which cannot be precipitated fror 
the acid sulution by means of caustic alk 
and, therefore, is not an earthy sa!t. Notwit 
standing this, however, we can always obta 
evidence of the existence of phosphate — 
lime in considerable proportion by incinerati 
mucus ; and Berzelius considers the tart 
formed on the teeth to be derived from t 
source. This form of mucus is consider 
by Berzelius to approach very nearly to 
obta.ned from the stomach and intestines: | 
differs greatly from nasal mucus, which 
sulub!e in the sulphuric and nitric acids. 
Intestinal mucus—The mucus of the stom: 
and intestines can be best obtained by washi 
the mucous surfaces of those organs tal 
from an animal that has fasted some he 
it is occasionally observed adhering — 
crement. This mucus, when dried, 
longer capable of assuming the ter 
character on being moistened with wat 
according to an observation of Berzeli 
quires an alkaline solution for burps 
it is coagulable by the acids. The acetic 
acts powerfully upon it, solidifying it” 
pletely. None of the acids dissolve it; 
acetic acid seems, however, to have a | 
action, since the liquor obtained by dige 
it is precipitab'e by the addition of it 
of galls, but not always, by the ferrocys 
of potassa. ‘The caustic a!katies dissolve 
mucus, and the addition of acids preci 
it when thus brought into solution, 
Mucus of the gall-bladder has been exan 
and appears to resemble that last d 
it is insoluble in the acids and pr 
by them from solution in alkalies. 
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