TRANSACTIONS Of SKCTION B. 543 



Biebrich scai-let, R, . . gives a blue-black or deep purple. 



„ B. . . „ bluish-green. 



Aniline scarlet . . . „ golden yellow, permanent on heating. 



Indulin „ slaty-blue to indigo, according to shade 



of the dye. 

 Rosaniline, Regina, and all violets „ yellow, or brownish-yellow. 



Phenyl and Dipheuylamine blues „ dark brown solutions. 



Iodine green \ bright yellow solutions, the former giving 



Malachite greeu . . . . J off iodme on heatuig. 

 Oitronine .... gives a pale cimiamon or neutral tint. 



After vitriol the action of concentrated hydrochloric acid may be next tried, which 

 distinguishes at once between saffi-anin and Biebrich scarlet, the former giving a 

 \'iolet solution, and the latter being precipitated as a red flocculent powder. 



Proceeding ia this way, and combming the observations with the dyer's usual 

 test, every one of the substances named can be readily identified, and much time 

 saved in the examination of dye-stuffs. 



5. On the Density of Fluid Bismuth. By W. Chandler Roberts, F.B.S., 

 and Thomas Wrightson, G.E. 



Some time since one of us described" the results of experiments made to de- 

 termine the density of metallic silver and of certain alloys of silver and copper 

 when in a molten state.^ The method adopted was that devised by Mr. R. Mallet/ 

 and the details were as follows : — 



A conical vessel of best thin Low-Moor plate (1 millimetre thict), about 16 

 centimetres hi height, and having an internal volimie of about 540 cubic centi- 

 metres, was weighed, first empty, and subsequently when filled with distilled water 

 at a known temperature. The necessary data were thus afforded for accurately 

 determining its capacity at the temperature of the air. Molten silver was then 

 poured iato it, the temperature at the time of pourmg being ascertained by the 

 calorimetric method. The precautions, as regards fiUuig, pointed out by Mr. Mallet, 

 were adopted ; and as soon as the metal was qviite cold, the cone vnth its contents 

 was agaiu weighed. 



Experiments were at the same time made on the density of fluid bismuth, and 

 two determinations gave the following results : — 



10-0051 innQQ 



1 rj.Qyg \ meau, 10"0d9. 



The invention of the oncosimeter ^ appeared to afford an opportunity for re- 

 simiing the investigation on a new basis, more especially as the delicacy of the 

 instrument had abeady been proved by experiments on a considerable scale on the 

 density of fluid cast-u'on. The following is the prmciple on which this instrument 

 acts : — 



If a spherical ball of any metal be plimged below the siuface of a molten bath 

 of the same or another metal, the cold ball "will displace its own volume of molten 

 metal. If the densities of the cold and molten metal be the same there will be 

 equilibrium, and no floating or sinking effect will be exhibited. If the density of 

 the cold be greater than of the molten metal, there wiU be a sinking effect, and if 

 less a floating effect when first immersed. As the temperature of the submerged 

 ball I'ises, the volume of the displaced liquid will increase or decrease according as 

 the ball expands or contracts. In order to register these changes the ball is himg 

 on a spiral spring, and the slightest change in buoj'ancy causes an elongation or 

 contraction of this spring which can be read off on a scale of ounces, and is re- 

 corded by a pencil on a revolving driun. A diagram is thus traced out, the ordinates 



' Proc. Hoy. iSoc. vol. xxiii. p. 493. 

 - Proc. Moij. Soc. vol. xxii. p. 366 and vol. xxiii. p. 209. 

 ' Jourii. Iron and Steel Inst. No, 2. (1879), p. 418. 

 < Ibid. No. 1. (1880), p. 11. 



