U R I

U R I

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ftallized form. This calculus, when calcinedin the open air, blackens, and gives an animo-niacal fmell and the other produ&s of i'oftanimal matter, and a white powder finally re-mains, which confifts of quick-lime and phof-phat of lime. The quick-lime is that portionof this earth which was united to the oxalicacid, and its produdtion or complete calcina-tion is a perfectly diltinguifhing mark of thisfait, as no other calcareous fait has yet beendifcovered in calculus but the phofphat, andt-lie acid of this latter is not deftrudtible by fire.

The very extenfive and accurate refearches ofMsflrs. Fourcroy and Vauquelin , on urinarycalculi, have difcovered to them the twelvefollowing diftindt fpecies, with the enumera-tion of which we ihall conclude this article,referring the reader to the original for a morecomplete defcription. 1

Sp. I. Calculi of Uric Acul alone.

Thefe, which the moll frequently occur, arediftinguifhable by their refemblance to wood incolour, by having a denfe radiated texture, andby being entirely folublc in cauftic alkali, with-out giving any fmell. Their analyfis has beenalready mentioned. Sp. gr. — 1.27 to 1.78.

Sp. 2 . U> at of Ammonia.

Thefe are pale-brown, difpofed in fine brittlelaminte, with a nucleus in the middle ; foluble incauftic alkali, with difengagement of ammonia.Muriatic acid takes away the ammonia and leavesthe uric acid pure. Sp. gr. 1.225 to 1.720.

Sp. 3. Oxalat of Lime. Mulberry Calculi.

The colour of thefe calculi is brown ; thefurface mamillated, fometimes approaching toprickly ; they are hard, denfe, and take a finepolilh ; atid when fawn give out the fmell ofrafped bone. They are infoluble in cauftic alka-lies, foluble in acids, and when calcined leavepure lime. 'They alfo abound with an animalmatter, like gelatin. Sp. gr. = 1.428 to 1.976.

Sp. 4. Uric Acid and Earthy Phofphats, intwo dif inB layers.

Their colour is white like chalk, they arefriable, and contain a nucleus of uric acid,and the phofphats externally. They can onlybe diftinguifhed when fawn through. Sp. gr.very variable.

Sp. 5. Uric Acid and Earthy Phofphats in-termixed.

I he external characters of thefe calculi areextremely variable. Sometimes they appear ho-mogeneous, at other times they are marbled orveined hke the onyx. The colour is grey,never of a chalk white, and they are often foapyto the touch. Sp. gr. 1.213 to 1.739.

* fourcroy's Syi.cme, &c. ton

Sp. 6. Urat of Ammonia and Earthy Phof-phats , in diftinSl layers.

Thefe referable Sp. 4. in appearance, and canonly be diftinguilhed by analyfis. Generallythe nucleus is the urat, and the phofphats areexternal; but fometimes it is the reverfe. Sp.gr. 1.312 to 1.761.

Sp. 7. Urat of Ammonia and Earthy Phof-phats intermixed.

Thefe are fcarcely diftinguifhable but byanalyfis. Their texture appears at firft veryuniform, but attentive examination will (hewtheir diltindt laminte of the component falts.

Sp. 8. Phofphat of Lime and Ammomaco-Magncfian Phofphat.

This fpecies is of a pure chalk-white, friable,infoluble in alkalies, diilolves in weak acids:fometimes it is of an enormous fize. Sp. gr.only from 1.138 to 1.471.

Sp. 9. The nucleus Oxalat of Lime, andcovered with a thick coating of Uric Acid .

This variety can only be diftinguifhed bythe eye when fawn through, when each fub-ftance may be recognifed by its peculiar marks.,Sp- g r - = 34 i to 1.754.

Sp. 10. A nucleus of Oxalat of Lime, and in-vefed with earthy Phofphats.

This too requires to be fawn through to hediftinguilhed. It is not uncommon. Sp. gr.= 1.168 to 1.752.

Sp. ix. Ut ■ic Acid or Urat of Ammonia, earthyPhofphats, and Oxalat of Lime.

Sp. 12. Uric Acid , Urat of Ammonia, earthyPhofphats, and Silex.

This is made a diftinft fpecies on account ofthe filex, which however is very rare.

The above claffification appears to us fome-what too complicated, and many other varietiesmight doubtlefs be found which would have asgood a claim to be confidered as diftindt fpeciesas fome of thofe here enumerated. It will fervehowever to {hew the very various nature ofurinary calculi, and the total abfence of any onecommon chemical property; and hence may bedemonftrated the impofiibility of finding a finglefolvent which would apply to every cafe of thisformidable difeafe.

URINE. Harn. Germ.

Human urine is an extremely compound fluid,but one with the nature of which we are nowvery accurately acquainted on account of themany excellent and accurate analyfes partial urcompleat which it has undergone from feveralexcellent chemifts, among whom we may par-ticularly mention Mr. Cruikfhank m , and a moltelaborate and mafterly analyfis by Mefir*.10. " See Rollo on Diabetes.

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