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/lit29465/1281/
URINE. 1271 
He states its quantity as equal to that of 
the lithic acid, in all persons feeding on a 
mixed diet. This, however, is certainly an 
over statement. It is present, but in small 
proportion, in healthy urine. 
The ultimate composition of hippuric acid 
is as follows : — 
C 18, II9, N 1, 0 6. 
It crystallises in four-sided prisms, obliquely 
truncated. 
When heated it gives out an odour resem¬ 
bling that of the tonquin bean. 
Lactic acid. — The lactic acid was first dis¬ 
covered in the urine by Berzelius, who ex¬ 
tracted it by the following process : — 
A portion of urine was evaporated to dry¬ 
ness, and alcohol of specific gravity 0*833 
boiled on the solid residuum. 
The alcoholic solution was next evaporated, 
and the mass dissolved in water. 
The watery solution was then boiled with 
a considerable quantity of hydrate of lime, 
till all ammoniacal fumes (from decomposing 
urea) were dissipated ; the hydrate of lime 
now became coloured yellow, owing to the 
decomposition of animal matter. 
The colourless solution was filtered, dried, 
and then treated with alcohol of specific 
gravity *845. Equal parts of strong sulphuric 
acid and water were now added, guttatim, to 
the alcoholic solution, until sulphate of lime 
no longer precipitated ; the clear liquor being 
decanted was next treated with carbonate of 
lead (recently precipitated), and was then 
filtered and evaporated to dryness. 
The residue was treated with oxide of lead 
and a little water, by which means the lactic 
acid was converted into a sub-salt of consider¬ 
able insolubility. This was collected, washed 
with water, and then decomposed by sul¬ 
phuretted hydrogen. Thus, sulphuret of lead 
subsided, leaving the lactic acid free in the 
supernatant liquor, which, by evaporation, 
yielded it in the form of an acid yellow syrup, 
exceedingly deliquescent, and incapable of 
being thoroughly dried by heat. 
Its chemical properties are the following : — 
It gives out an acrid odour* when heated, 
and leaves a porous charcoal if the heat be 
continued. Alcohol dissolves it in all propor¬ 
tions. It is nearly insoluble in ether. 
Tts salts are all of a gummy and uncrystal- 
lisable nature, excepting the lactates of zinc 
and magnesia, which have been obtained in a 
crystalline form. 
When lactic acid is added to a strong solu¬ 
tion of the acetates of magnesia or oxide of 
zinc, the lactates of those bases are pre¬ 
cipitated. ... 
The existence of lactic acid, as a consti¬ 
tuent of urine, has been denied by Liebig, and 
the question is as yet far from being satisfac¬ 
torily settled. 
The admission made of late by Liebig, how¬ 
ever (as the result of his researches on muscle), 
that lactic acid exists in the juice of flesh, 
gives great probability to the correctness of 
Berzelius’s statement. 
* Not unlike that of the tartrates. 
The other constituents of the urine which 
1 have enumerated, require no particular 
notice in this place ; and for the methods of 
quantitatively examining the fluid, I must 
refer to the article Organic Analysis, 
contained in this work. 
Healthy urine possesses the following phy¬ 
sical characters : — It is of a pale straw colour, 
limpid and acid ; after standing some hours, 
it deposits a light, flocculent sediment, com¬ 
posed of mucus. This mucus, as it exists 
in health, suspended in the urine, does not 
materially interfere with the transparency of 
the fluid. The odour of urine is peculiar, and 
subject to modification from the use of various 
articles of diet, and remedies. Its specific 
gravity varies, owing principally to two causes 
— the condition of the atmosphere, as affect¬ 
ing the proportion of water exhaled by the 
skin, and the quantity and quality of the in- 
gesta taken. 
Healthy urine may, under these considera¬ 
tions, be said to vary in specific gravity from 
1004; to 1032 ; while perhaps, under ordinary 
or average conditions of diet, temperature, &c., 
we may place its specific gravity at 1015 to 
1022. 
Quantitative composition of healthy Urine.— 
The quantitative composition of urine must of 
course vary considerably, owing to the condi¬ 
tions noticed above, as affecting its specific 
gravity. The following is the result of an 
analysis made on 1000 parts by Berzelius, on 
a specimen considered as healthy: — 
Water...... 933*0 
Urea ------ 30*10 
Free lactic acid - - - 
Lactate of ammonia - - -1 
Extractive matters (alcoholic and j 
watery) - - - - -J 
Lithic acid ----- 1*00 
Vesical mucus - 0*32 
Sulphate of potassa - - - 3*71 
Sulphate of soda - - - - 3*16 
Phosphate of soda - 2*94 
Superphosphate of ammonia - - 1*65 
Chloride of sodium - 4*45 
Chloride of ammonium - 1'50 
Phosphate of lime and magnesia - 1*00 
Silicic acid ----- 0*03 
Dr. Bence Jones has experimented very 
carefully on the acidity of urine in health. His 
results show that the amount of acidity is 
always varying. Thus the urine passed longest 
after food was generally the most acid, and 
that voided while digestion was going on, 
much less so, and in some cases even alkaline, 
though the patient was in perfect health. 
These conditions pertained, whether a pure 
vegetable or animal diet was taken. In the 
case of a pure vegetable diet, however, the 
decrease in acidity, after taking food, was not 
so marked as when a pure animal diet was 
observed; the urine in the latter case.some¬ 
times becoming highly alkaline, but in the 
former never exceeding neutrality. 
Other analyses of more recent date have 
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