40 Mr. T. Taylor on some 



dilated ureter or from the common cloacal termination of the 

 gut of the fish. 



These concretions have generally a flattened oval figure, 

 their centre being often depressed or slightly concave. They 

 vary considerably in size, but are usually about that of a hen's 

 egg. Their surface is unequal but quite smooth, and of a 

 yellowish-white colour. When broken they present a highly 

 crystalline structure, consisting of fine plates or needles ra- 

 diating from the centre to the circumference, but which are 

 made up of very thin concentric layers adhering firmly toge- 

 ther. Fragments of these calculi are translucent, and their 

 interior is of a pure white colour. They are exceedingly 

 scarce, and are highly esteemed for their supposed medicinal 

 virtues. Dr. Cook informs us that the powder is highly com- 

 mended as a diuretic and lithontriptic, and that the common 

 people in the neighbourhood of the Volga take from ten to 

 sixty grains, scraped fine in a little water, three or four times 

 a day when the case is dangerous. 



The composition of these calculi was first determined by 

 Klaproth, but the earliest description of them is to be found 

 in the Philosophical Transactions for 1748. 



The specimen analysed by Klaproth had been received 

 from Prof. Pallas. It weighed above seven ounces troy, and 

 consisted of albumen I, water 24, phosphate of lime 71*50, 

 sulphate of lime 0*50. 



17*13 grs. of one of the specimens in this collection, previ- 

 ously calcined, gave by solution in dilute muriatic acid and 

 precipitation by oxalate of ammonia, 13*87 grs. of carbonate 

 of lime, which is = 17*54 of the diphosphate of lime; 100 grs. 

 of the same calculus gave — 



By calculation. 



Water 26*33 25*60 = 5 atoms. 



Organic matter . . 0*40 1*13 



Diphosphate of lime . 73*27 73*27 = 1 atom. 



100*00 100*00 



The Beluga stones therefore consist of an atom of diphos- 

 phate of lime combined with 5 atoms of water. The water is 

 necessarily over-estimated in the analysis, on account of the 

 organic matter being partially soluble in the diluted acid. 



By another and more rigid analysis, I found the calculus 

 to consist of 32-21 CaO, 40*33 P0 5 , and 26*33 HO, which 

 would give 72*54 per cent, of diphosphate of lime. This cal- 

 culus has also been analysed by Prof. Wohler, who ascer- 

 tained that four of the five atoms of water are driven off at 

 392° Fahr., while the last atom is expelled by a red heat. 



