120 Scientific Intelligence. 



the centre of a beam of wood, even if immersed in water, as the water 

 enters with great difficulty into wood ; and the solution itself cannot be 

 introduced without forming a vacuum in the saturated vessel, and so 

 removing all the air from the wood. 



The first time I used this solution I found a large quantity of mould 

 formed, and indeed it contains all the elements to increase its growth. 

 The second time the solution was boiled in an iron vessel, and no mould 

 formed on it; on the contrary mould was destroyed by it. The sul- 

 phate of ammonia dissolves iron rapidly, and forms a double salt which 

 is deleterious to such growths. I imagined any other metallic salt 

 would do, and used ordinary chlorid of manganese prepared in the lab- 

 oratory, which killed all such fungi rapidly, and no more have grown 

 after standing eleven months in contact with organic matter. 



I believe there are many ways in which this may be used. My wish 

 was to find a substance suited for building fire-proof ships, and I believe 

 this would do; at any rate the ships would be fire-proof, experience 

 could alone tell if any other objection followed. It does not render the 

 wood hard, heavy or brittle. 



I believe it would be of the greatest advantage in mills, which now 

 suffer so much from fire, diminishing or rather entirely removing the 

 expense of insurance. It does not hurt colors; so that even colored 

 goods might be dipped when kept long in one place, or when sent in 

 vessels abroad. Possibly some delicate colors may be attacked, but 

 this must be a rare case. 



I am more desirous of seeing ships built of an incombustible mate- 

 rial, the means of escape at sea being few, and confined to few ; and 

 whilst there is any hope of doing it easily, I scarcely think it proper 

 for any one to neglect what information may exist on the subject. 



II. Mineralogy axd Geology. 



1. Randanite, a native hydrated Silica from Algiers; by M. Sal- 

 vetat, (Ann. de Ch. et de Phys., Nov., 1848, t. xxiv, p. 348.)-— This 

 hydrated silica exists abundantly near Algiers, and was taken for Kao- 

 lin. It is pulverulent and friable, forming an excessively light powder. 

 It is infusible, but loses color and becomes grayish, contracting a little. 

 It gives up water at 16° C, but still retains a portion at 100° C, losing 

 the whole only at an intense heat. It was found to consist of 80 parts 

 of gelatinous silica, 9 of water, 6*48 of insoluble silica, with 1*41 alu- 

 mina, 0*55 oxyd of iron, 0"56 lime, 2-00 of potash, soda and loss, and 

 a trace of magnesia. Of the water 4*04 per cent, escaped at 16° C, 

 and 3*96 at 100° C, and 1 per cent, is combined with the alumina. 

 Neglecting what is obviously foreign to the mineral, it has the formula 



• • * 



. . . 



Si 2 II when simply dried at 16° C, and Si 4 II when dried at 100° C. \ 



The composition resembles that of a similar material from Ceyssat, 

 and near Randan, in the Puy de Dome, analyzed by M. Fournet. This 

 chemist obtained in his analysis, gelatinous silica 87*20, water, car- 

 bonic acid and organic matters 1000, alumina and oxyd of iron 2 00, 

 sand by decantation 0*80, with traces of lime, magnesia, &c. 



