72 Mn. Crum on the Action of Bleaching Powder, fyc. 



the water was poured away, and the cream of lime which remained 

 corked up in small bottles for uso. By this means I had always at 

 hand a quicklime, whoso equivalent I know, free from sand and free 

 from carbonate. Marble, of course, answers best for this purpose. 



Manganese again appears in tho nitric acid which has been employed 

 to decompose the plumbate, in the state of the pink-coloured hyper- 

 manganic acid. When this solution is poured off, and more water and 

 nitric acid added to the peroxide that is left, a small quantity of sul- 

 phate of manganese restores the colour. Peroxide of lead, prepared 

 by the same, or by other means, when dried, does not yield the pink 

 colour without the application of heat. Ten grains of Irish lime 

 dissolved in nitric acid, and heated with water containing nitric acid 

 and peroxide of lead, yielded a pink solution as deep as that produced 

 in similar circumstances from one-hundredth of a grain of sulphate of 

 manganese. That species of lime may therefore be presumed to con- 

 tain tqVjIT °f * ts weight of manganese. White marble, even, is found 

 by this test to be not altogether free from manganese. 



2d April, 1845. The President in the Chair. 



Messrs. Robert Salmond, John Smith, LL.D., James Mitchell, and 

 William G. Miller, were admitted members of the Society. 



Dr. Nichol gave a short description of the methods of observation 

 in use at the Glasgow Observatory. Mr. Lawrence Hill, jun. exhibited 

 and described a model of a Self-acting Railway Break. The President 

 having vacated the chair, it was taken by the Vice-President, who 

 stated that the council had resolved to recommend to the Society that 

 the President be respectfully requested to sit for his portrait, to be 

 preserved in the Society's hall, from which an engraving might after- 

 wards be taken. The proposal was cordially and unanimously enter- 

 tained by the meeting, and a subscription immediately commenced. 



lQth April, 1845. The President in the Chair. 



Mr. John Thomson, Annfield, and Mr. David Chambers, were 

 elected members. 



Mr. Michael Scott read a paper on a new hydraulic machine, stated 

 to be applicable as a substitute for the air pump in marine steam 

 engines, also to the pumping of ships, and to the raising of water on 

 shore. 



