Intelligence and Miscellaneous Articles, 561 



a degree below their freezing-points, which had been approximately- 

 ascertained by preliminary experiments, and then, by means of a 

 small piece of ice, he occasioned a slight freezing of the solutions. 

 In these, as in his former experiments, it was observable that the 

 lowering of the freezing-point was in a certain manner proportional 

 to the quantity of salt dissolved, if it is assumed that in some solu- 

 tions the salt is dissolved in the anhydrous, and in others in the 

 hydrated state. For instance, solutions of hydrochloric acid contain 

 the compound H CI +12 HO; solutions of sulphuric acid, the 

 compound SO + IOHO; of chloride of copper, CuCl + 12HO; 

 of protochloride of manganese, Mn CI-}- 12 HO; of caustic soda, 

 NaO+4HO; of caustic potash, KO + 5HO ; of ammonia, NH 4 

 + 2HO. 



Experiments with solutions of chloride of copper showed that 

 solutions containing less than 20 per cent, of chloride of copper 

 hold in solution the compound CuCl+12HO, and solutions con- 

 taining more of the; copper-salt the compound CuCl-}-4HO. 



This change in the constitution of the solution, which is recog- 

 nizable by means of the freezing-points, is accompanied also by a 

 change in the colour of the solutions, — those which contain the salt 

 CuCl + 12HO being blue, while those which contain CuCl + 4HO 

 are green. The author had previously detected a similar case of 

 change in the constitution of a saline solution, unaccompanied, it is 

 true, by change of colour, in the case of chloride of sodium, which 

 dissolves at common temperatures as an anhydrous salt, but below 

 — 9° C. is contained in solution in combination with 4 equivalents 

 of water. 



The experiments with solutions of sulphuric acid show that they 

 contain the compound S0 3 -flOHO. It is proved by experiments 

 on the electric conducting power of liquids that both water and 

 anhydrous sulphuric acid are exceedingly bad conductors of elec- 

 tricity, but that a good conductor is formed by the combination of 

 the two ; the compound which offers the smallest resistance to the 

 passage of electricity is, however, not the first hydrate, nor even 

 the second, but, according to Wiedemann's determinations, the one 

 which contains in 100 parts 45*8 parts of anhydrous sulphuric 

 acid. This composition corresponds almost exactly with the formula 

 SO 3 -f 10 HO : whether this coincidence is anything more than acci- 

 dental, must for the present be left undecided. — Monatsbericht d. K. 

 Preuss. Akad.d. Wissenschaften zu Berlin, 1862, p. 163 (March 6). 



ON THE COMPOSITION OF MINERALS CONTAINING NIOBIUM. 

 BY PROFESSOR H. ROSE. 



The most important class of minerals containing niobium are the 

 columbites, which appear to occur in nature much more plentifully 

 than the other niobiferous compounds, most of which are still among 

 mineralogical rarities. Several of these minerals have been analysed 

 in the author's laboratory. 



Samarskite. — This remarkable mineral, first described by Professor 

 G. Rose and named by him uranotantalite, has been examined at 



Phil. Mag. S. 4. No. 157. Suppl. Vol. 23. 2 P 



