PATHOLOGY. 
348 
the views we have entertained of calculous diforders, (fee 
Diabetes,) viz. that they all confift in a peculiar change 
in the fecernents of the kidneys, probably independent 
of the ftate of the blood, and confequently under 
the control of the nervous fyftem, has received much 
fupport from the teftimony of a recent diftinguifhed au¬ 
thor, Dr. Prout, who (in his Inquiry into the Nature 
and Treatment of Gravel) in every page refers to the dif- 
ordered date of the nervous fyftem as a caufe of morbid 
depofitions. We do not conceive that this opinion is at 
all impugned by the relief afforded in fome cafes by the 
exhibition of remedies oppofite in their chemical proper¬ 
ties to thofe of the calculi, becaufe fuch medicines may 
aft by caufing a different aftion in the kidneys. The 
afl’umption of this idea explains how it happens, that it 
is only in fome cafes that the above remedies do good ; 
fince, that fuch failure fhould occur in medicines which 
aft on difordered veffels, no one can be furprifed at; but, 
that the uniform and invariable operation of chemiftry 
fhould be fo often difturbed muft be a matter of the 
greateft wonder to thofe who conceive that thefe opera¬ 
tions are the caufe of calculi. To return to our hiftory 
of the fpecies of calculi. 
i. Lit hie Acid Depofitions .—Lithic acid is feparated 
from the urine in two forms, as fediment or as calculus. 
In the firft form it is in combination with ammonia; in 
the fecond, pure. In the former ftate it is precipitated 
llowly, and acquires a reddifh hue ; in the latter the li¬ 
thic acid forms a hard inodorous concretion, of ayellow- 
ifli or brown colour, fimilar to that of wood, of various 
lliades. According to profeffor Murray, calculi of this 
kind are in fine clofe layers, fibrous or radiated, and ge¬ 
nerally fmooth on their furface, though fometimes a lit¬ 
tle rough. They are rather brittle, and have a fpecific 
gravity varying from i - 276 to i' 786, but ufually above 
1-500. One part of lithic acid is faid to diffolve in 1720 
parts of cold water, and 1150 parts of boiling water ; 
(Marcet, p. 65.) and this folution turns vegetable blues 
to a red colour. When it has been diflolved in boiling 
water, fmall yellowilh cryftals are depofited as the fluid 
becomes cold. Lithic acid calculi blacken, but are not 
melted by the blow-pipe, emitting a peculiar animal fmell, 
and gradually evaporating until a fmall quantity of 
white alh remains, which is alkaline. By diftillation, 
they yield ammonia and pruflic acid. They are foluble 
in the cold, in a folution of pure potafl'a, or foda ; and 
from the folution, a precipitate of a fine white powder is 
thrown down by theacids. Lime-water likewife diflolves 
them, but more fparingly. In folutions of the alkaline 
carbonates, they remain, according to Scheele, unchanged: 
according to the experiments of Dr. Egan, however, they 
are diflolved even by a weak folution, and alfo when the 
acid is fuperfaturated by carbonic acid. (Tranf. of Iriflt 
Acad. 3805.) They are not much afted upon by ammo¬ 
nia. They are not foluble either in the muriatic or ful- 
phuric acid; though they are fo in the nitric, when af- 
iifted by heat; and the refidue of this folution, when 
evaporated to drynefs, a flumes a remarkably-bright pink 
colour, which difappears on adding either an acid or an 
alkali. In many of thefe calculi, the lithic acid is nearly 
pure; in others, there is an intermixture of other ingre¬ 
dients, particularly of phofphate of lime, and phofphate 
of ammonia and magnefia; and, in almoft all of them, 
there is a portion of animal matter, which occafions the 
fmell when they are burnt, and the lofs in their analyfis. 
The depofition of lithic acid, either in the form of 
fediment, gravel, or calculus, is almoft always connefted 
with indigeftion. According to fome, the dyfpepfia is 
the confequence of an excefs of acid being generated in 
the ftomach, from the morbidity of that organ fuft'ering 
chemical changes to take place in it. But, as the pre- 
fence of this free acid has not been detefted in the blood 
ingravelly cafes, we muft infer that the gaftric irritation 
caufed (by means of fympathy) in the urinary fecernents is 
the fame aftion as is excited in thofe of the ftomach ; an 
opinion which, though it aflumes a. fympathy not in ge¬ 
neral very apparent, is neverthelefs poflible. Dr. Prout 
gives another very plaufible account of this matter; one 
which, while it aflumes the exiftence of difeafed blood in 
thefe cafes, clearly Ihows why we do not find any free 
acid in the blood, and confequently that the difeafe de¬ 
pends on morbid aftion of the kidneys/ induced by the 
morbidity of their fanguineous fupply. This important 
principle is, that, if imperfectly ajjimilated or unnaturally 
albuminous matter is brought to the kidney, it does, and 
muft, in virtue of its natural aftion, convert fuch imper- 
feft albumen into lithate of ammonia. 
The treatment of perfons labouring under the above 
form of difeafe will not be difficult, whichever of the 
above theories we adopt; except that, under the influ¬ 
ence of the former, our exhibition of alkaline remedies 
will of courfe be more free. We are bound in juftice to 
declare, however, that the fuccefs which attends thefe 
remedies rather militates againft than argues for, the the¬ 
ory in queftion ; for they are very often quite ufelefs. 
The molt fuccefsful praftice feems to be, to alter the diet 
in fome eflential points ; but at the fame time to attend 
rather to its quantity than to its quality; to excite the 
biliary and inteftinal fecretions by blue pill and gentle 
purges, and thofe of the fkin by means of antimonials. 
In thofe yellow depofitions (confifting of lithate of 
ammonia), indicative of dyfpepfia, the fame treatment 
is to be followed. Thofe pink depofitions from urine, 
which are compofed, according to Prout, of the purpu- 
rates of foda and ammonia, and which are ufually met 
with in chronic phlogofis and heftic fever, and almoft 
always in acute inflammations, do not of courfe require 
that any change fhould be made in the ordinary courfe 
of treatment on their account. 
Thofe fudden acceflions of pain and inflammation 
which are called fits of gravel are more efpecially treated 
by low living, copious dilution, and full doles of hyo- 
feiamus. 
2. Depofitions of which Phofphoric Acid forms a part .— 
Phofphoric acid and lime, magnefia and ammonia, are 
all natural conftituents of urine. A depofition of one 
or more of thefe alkalies, in combination with phofpho¬ 
ric acid, conftitutes a very common form of difeafe. It 
is prefumed that the phofphoric depofition may occur in¬ 
dependently of any morbid change in the kidney, as when 
foreign bodies get by chance into the bladder, and form 
a point of adheiion for thefe falts ; a change we fhould 
not be furprifed at, when we obferve the very common 
occurrence of urinary cryftallizations in fituations exter¬ 
nal to the body. It has been doubted, however, by fome, 
whether even foreign bodies do not operate by exciting 
irritation, and conlequently morbid fecretion of urine. 
At all events, the derangement of the aftion of the kid¬ 
ney is the commoneft fource of the phofphatic depofi¬ 
tion. This latter feems to confift in a fufpended or di- 
miniflied aftion of the ufual acidifying powers of the 
kidney, whereby, inftead of lithic acid, a greater quan¬ 
tity of urea (equivalent to ammonia), lime, and magne¬ 
fia, is generated. This condition of the urine is very 
commonly dependent upon a deranged ftate of the chy- 
lopoi'etic vifeera ; frequently, too, it is connefted with a 
great degree of irritability and debility of the fyftem. 
Hence it is that children are fo liable to this form of de- 
pofite, from their extreme irritability, and great ten¬ 
dency to diforders of the ftomach and bowels. 
The depofition of the phofphates is attended with un- 
eafinefs about the loins, a fallow haggard countenance, 
black, clay-coloured, or yeafty, ftools, and fubfequentiy 
great languor and debility, as in diabetes. The urine 
too here, as in the difeafes already treated of, is pale, 
and fecreted in larger quantity than natural; but it is 
commonly of very low fpecific gravity, fuch as i'ooz. 
When the fpecific gravity is greater than this, the phof¬ 
phatic fediment is proportionally more copious. In this 
ftate of difeafe the urine is very prone to decompofitiori; 
1 and 
