190 Dr. Proufs Description of an Apparatus for [March, 



that with large shining spots ; but according to the colour into 

 the blackish, yellowish, and reddish. 



Sect. 19. Of the Siirme and Tutia {query Antimony ?). — it is a 

 bright, heavy, transparent, black stone, which is divided accord- 

 ing to the country where the mines are situated, into those o* 

 Ispahan, Herat, Sabuhstan, Georgia, and Kerman. The first is 

 the best, the last the worst ; if powdered Siirme is applied to the 

 eyes, it increases their polish. The tutia (the genuine eye-paint), 

 is divided into those ot Kerman, Kand, India; the last is pure 

 and white like salt; that of Kerman yellowish. It is made by 

 laying the natural tutia stone upon coals, and catching the 

 vapour in an akmbick upon nails. The lightest tutia, and the 

 best for the eyes, is that which forms on the points of the nails, 

 the second sort on the middle, and the coarsest sort on the 

 heads of the nails. The Indian is produced on the shore of the 

 ■ea, and is much used in alchemy. 



Sect. 20. Of the Proportions of some precious Stones to others. 

 •—Abu Kihan is said to have found by experiment that a miskal 

 of blue jakut is equal in size to five dank* and three tissu of 

 red jakut, or to five dank and two and a half tissu of laal; and that 

 four dank minus a tissu of coral are equal in size to four dank minus 

 two tissu of onyx and crystal. The mode of discovering the size and 

 weight is the following : a vessel is filled with water, and the 

 stones thrown singly into the water; the quantity of water which 

 is expelled from the vessel by means of each stone is equal to 

 the room it occupies. God knows best. 



Article VI. 



Description of an Apparatus for the Analysis of organized 

 Substances. By W. Prout, M.D. F.R.S. &c. 



There is nothing new in the principle upon which the analy- 

 tical process is conducted by the following apparatus. The sub- 

 stance to be analyzed is introduced into a glass tube, G (PI. CII), 

 (about ith or -^th of an inch in diameter, and 10 inches long) 

 mixed with the requisite quantity of the black oxide of copper, 

 precisely in the same manner and with the same object explained 

 by me in a former paper on this subject.* The tube above-men- 

 tioned is inserted firmly into a piece ofcorkatits upper and open 

 end in such a manner that about half an inch of it may project 

 beyond the larger end of the cork. The cork is then placed in 

 the conical hole in the piece of brass, C (fig. 2), fixed in the 



♦ According to Meninski, a dank is equal in Egypt to three carats ; actoriling to 

 Cassira, two in Spain. It is the fdurlh part of a drachm, bnt according to l''er- 

 Jieng the sixth. Tlie lissit, acoordingto Ferheng, weighs somelim^s two, somelimei 

 four barley corns; and the miskal is one drachm and a half.. 



+ See Med. Chirurg. Trans, vol. viii. p. 526. 



