Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 4: Pla [corr.: Ple] - Wri
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit29465/426/
416 
SALIVA. 
globules are remarkably transparent, and 
smaller than the more opake. 
Specific gravity. — The specific gravity of 
healthy saliva is about 1007*9, according to 
the experiments of Dr. Wright. It is denser 
after food has been taken. Mitscherlich gives 
the specific gravity of saliva at 1006*1 to 
1008*8, which agrees with Dr. Wright’s ob¬ 
servations. 
Some discrepancy of opinion exists as 
to the reaction of saliva in respect to alka¬ 
linity or acidity. Tiedemann and Gmelin, 
and also Schultze, state fresh saliva to be 
alkaline. The latter chemist, has, indeed, 
attempted to define its saturating power. He 
also considers that it may become acid if 
retained long in the mouth, and that its alka¬ 
linity when fresh is dependent on ammonia. 
This is denied by Mitscherlich, who says that 
no ammonia is given off when fresh saliva is 
heated, and that the alkalinity depends on the 
presence of a fixed alkali. 
I have myself found that saliva, so far 
from losing its alkalinity by evaporation, has 
this quality increased, and am inclined to re¬ 
gard the reaction as dependent on the pre¬ 
sence of tribasic phosphate of soda (a salt re¬ 
acting on test paper as an alkali), as has been 
stated by Enderlin. 
Chemistry.—Berzelius estimates the solids of 
saliva at about 1 per cent. From the solid re¬ 
sidue he extracted osmazome, an alkaline lac¬ 
tate, and chlorides of potassium and sodium by 
digestion with alcohol. That portion which 
the alcohol left undissolved consisted of soda, 
mucus, and a peculiar animal matter, which has 
been called “ salivary matter,” or “ ptyalin.” 
The mucus can be separated from this salivary 
matter and soda by digestion in cold water, 
which dissolves the two latter. The mucus 
thus separated by Berzelius yielded on in¬ 
cineration a large proportion of phosphate of 
lime. 
The following is his analysis of saliva : — 
Water..... 992*9 
Ptyalin.....2*9 
Mucus - - - - - 14 
Animal extractive matter and al¬ 
kaline lactates - - - *9 
Chloride of sodium - - 1*7 
Soda.....*2 
1000*0 
Tiedemann and Gmelin obtained from 1*14 
to 1*19 percent, of solid residue by evapo¬ 
rating saliva. From this, 0*25 parts of ash 
were obtained, of which 0 203 were composed 
of salts soluble in water, the remainder con¬ 
sisting of earthy phosphates. 
The following is a list of the constituents 
of the saliva, according to the above-men¬ 
tioned chemists : — 
1. Water. 
2. A substance soluble in alcohol, and in¬ 
soluble in water (fat containing phosphorus). 
3. Matters soluble both in alcohol and 
water (osmazome, chloride of potassium, lac¬ 
tate of potash, and sulpho-cyanuret of potas¬ 
sium. 
4. Animal matter soluble in boiling alcohol, 
but precipitated during cooling, with sulphate 
of potash and some chloride of potassium. 
5. Matters soluble in water only (salivary 
matter with abundant phosphate, and some sul¬ 
phate of an alkali, and chloride of potassium). 
6. Matters soluble neither in water nor in 
alcohol (mucus, probably some albumen, with 
alkaline carbonate, and phosphate). 
Mitscherlich gives the following analysis of 
the saline ingredients of saliva : 
Chloride of potassium - percent. 0*18 
Potash (in combination with 1 n.™. 
lactic acid) - - j 0094 
Soda.....0*024 
Lactic acid - 
Soda (combined with mucus) - 0*164 
Phosphate of lime - 0*017 
Silica ----- 0*015 
Simon made an analysis of his own saliva, 
and gives the following as the result : 
Fat containing cholesterine - 0*525 
Ptyalin with extractive matter - 4*375 
Extractive matter and salts - 2*450 
Albumen, mucus, and cells - 1*400 
Water..... 991*225 
Simon* adopted the following process in 
order to complete the above analysis. A 
known weight of saliva was first evaporated 
to dryness ; the loss of weight thus indicated 
the proportion of water. The residue was 
treated with ether, which extracted the fats. 
The solid mass remaining was next treated 
with water, which dissolved out the ptyalin, 
extractive matters, and salts, leaving behind 
mucus, albumen, and cells. 
Dr. Wright has experimented on saliva most 
industriously, and has entered at some length 
on the peculiarities of ptyalin, but evidently 
speaks of a very different constituent to that 
described by Berzelius and Simon. Accord¬ 
ing to the mode of analysis adopted by these 
two latter chemists, the ptyalin of Wright will 
be estimated with the fatty constituents, 
among which it most probably holds its proper 
place. 
His process of extraction is as follows :—“ To 
pass saliva through ordinary filtering paper, and 
after filtration shall have been completed, to 
exhaust the residue with sulphuric ether ; the 
ethereal solution contains a fatty acid and 
ptyalin. It is to be allowed to evaporate 
spontaneously, and the residue left by evapo¬ 
ration is to be placed upon a filter and acted 
upon by distilled water, which dissolves the 
ptyalin and leaves the fatty acid. If the aque¬ 
ous solution be carefully evaporated to dry¬ 
ness, the salivary matter will be obtained in a 
pure state. Ptyalin, thus prepared, is a nearly 
solid matter, adhesive, and of a yellowish co¬ 
lour ; it is neither acid nor alkaline, readily 
* In framing this article, much valuable informa¬ 
tion has been derived from Simon’s work on Phy¬ 
siological and Pathological Chemistry, translated 
by Dr. Day for the Sydenham Society.
        

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