Transactions of the Royal Society of Edinburgh. 349 



Brewster. — In a subsequent number of this Journal we shall direct the 

 attention of our readers very fully to the contrivances described in this pa- 

 per, which require numerous figures for their illustration. 



6. On the parasitic formation, of Mineral species. — In this number, p. 275. 

 and in No. xiii. p. 126, the reader will find the whole of this curious and im- 

 portant paper. 



7. On the influence of the air in determining the crystallization of Saline 

 Solutions. By Mr Thomas Graham. — When a phial is filled with a boil- 

 ing saturated solution of Glauber's Salt, and its mouth immediately stop- 

 ped by a piece of bladder tied tightly over it while it is hot, the solution 

 will cool without crystallizing, and will continue entirely liquid for hours 

 and even days, although it contains a great excess of salt. If the bladder, 

 however, is punctured, and the air admitted, the solution is immediately re- 

 solved into a spongy crystalline mass, with the evolution of muchheat. This 

 fact, which has long puzzled chemists, has been ingeniously and satisfactorily 

 explained by Mr Graham, who concludes from several experiments and facts, 

 that air determines the crystallization of supersaturated saline solutions by 

 dissolving in the water, and thereby giving a shock to the feeble power by 

 which the excess of salt is held in solution. 



The expansion of the whole mass when it becomes solid is shown by Mr 

 Graham to be entirely a momentary dilatation of the whole contents of the 

 phial, both liquid and solid, by the evolution of heat, which occurs at the in- 

 stant of crystallizing, and which always amounts to 20° or 30° Fahr. 



8. Mineralogical account ofthe ores of Manganese. By W. Haidinger, 

 Esq. — In an article On the crystalline forms and properties ofthe Manganese 

 ores, which Mr Haidinger published in this Journal, vol. iv. No. vii. p. 41 — 

 51, he had previously published the principal facts contained in the present 

 paper, He has added, however, under the head of Prismatic Manganese 

 Ore, the description of Pyrolusite, which, in order to complete the ar- 

 ticle in our seventh number, we have published in p. 304 of this number. 



9. Chemical Examination ofthe oxides of Manganese. By Dr Edward 

 Turner. — Dr Turner's able and elaborate Paper is divided into two parts 

 viz. 



Part. I. On the Atomic Weight of Manganese.— Analysis ofthe Carbo- 

 nate of Manganese. 



II. On the composition of the Ores of Manganese, described by Mr 

 Haidinger. 

 The following are the leading results of Dr Turner's analyses. 

 1. Carbonate of Manganese consists of 



Protoxide of manganese, - - 56.853 

 Carbonic acid, - 34.720 



Water, - - * - - 8.427 



100.00 

 VOL. IX. NO II. OCTOBER 1828. Z 



