174 ANNUAL OF SCIENTIFIC DISCOVERY. 



frequently above coal and lime, and both above, and mingled with, 

 sandstone. Mrs. Marshall's experiments show that if amass, in imita- 

 tion of such mineral bodies, be prepared, and one part of it left at per- 

 fect rest, while the other is agitated or disturbed, the one will harden 

 in a few hours or days into a substance not distinguishable by the eye 

 from the natural stone, and capable of resisting water and weather ; 

 while the latter will take as many weeks to harden, and then present a 

 mass which readily degrades by exposure to either. The experiment 

 may be varied thus : Such masses always set or harden from the 

 centre outwards ; allow the mass to set till within half an inch of the 

 surface ; disturb what remains, and the result will be, that, on making 

 a section, the centre will be found hard enough to take a fine polish, 

 while the outer crust will be a mere crumbling mass of chalk or sand. 



Mr. Hugh Miller, in his " Old Red Sandstone," conjectures that the 

 curious outstriking of colors, which here and there occurs in that and 

 some other formations, may have arisen from the action of decaying 

 animal matter. Not only is this completely proved by this lady's ex- 

 periment, but, what Mr. Miller seems not to have once suspected, that 

 decaying vegetable matter has the same effect ; and doubtless to this, 

 rather than animal, are owing the more curious and grotesque forms 

 in which these white and gray stains appear. 



We were particularly interested by one specimen, in which, with 

 the view of solving two problems by one experiment, there had been 

 laid down upon the surface, while yet fluid, a few of the delicately- 

 rounded leafstalks of the Fucus vesiculosus ; of these some had sunk only 

 half, and others wholly, under the surface. In course of time the veg- 

 etable matter shrinks to a film that can be blown out with the breath, 

 and there then remain in the mimic stratum perforations which are 

 lined with white, presenting the most perfect resemblance to those 

 mysterious worm-like borings which occur in the face of compact lime- 

 stone, and have given rise to so much discussion. Chambers^ Journal. 



TO MAKE ARTIFICIAL MARBLE OR STONE. 



THE following is the condensed specification of a patent granted to 

 St. Clair Massiah, and published in the May number of " Newton's 

 .Repertory of Inventions." The material of which the artificial stone 

 is made, is plaster of Paris. After it has been prepared, and is of the 

 right shape, it is dried in a room at about 80. When completely 

 dry, it is immersed in a warm solution of borax and glauber salts, pre- 

 pared by dissolving one pound of borax and a quarter of an ounce of 

 the salts in one gallon of water, as a ratio. After the casting is thor- 

 oughly wet in this, it is removed to the drying room, and exposed to a 

 heat of 250 Fahrenheit, until all the watery parts are thrown off. It is 

 then permitted to get nearly cold, when it is immersed in a strong hot 

 solution of borax, to which has been added one ounce of strong nitric 

 acid Tor every gallon of the borax solution. This solution is kept quite 

 warm, and the castings kept in it until they are completely saturated, 

 when they are taken out and dried, and found to have acquired a marble- 

 like hardness. A day or two after this operation, the castings are 



