64 Progress of Invention. 



erased, under the supposition, very probably, that it lessened the 

 value of the engraving. This discovery of another curious result 

 of photography immediately suggested its use as a means of re- 

 viving the effaced writing of palimpsests, and it is even hoped 

 that -what is thus recovered may be transferred directly to steel or 

 stone. 



Economic Source of Oxtgen. — Oxygen gas has of late become 

 of considerable importance in the arts, etc., and it is probable that 

 it would be employed for a still greater variety of purposes were it 

 not so dear anct difficult to be obtained. These obstacles to its more 

 general use are not likely to exist much longer. It may be very 

 easily and economically procured by acting on sulphate of lime at a 

 high temperature with silex, so as to form silicate of lime, sulphurous 

 acid, and oxygen ; and conducting the ga.seous mixture into a chamber 

 where it is exposed to a pressure of three atmospheres, which 

 liquefies the sulphurous acid. The oxygen, after having been 

 purified by transmission through lime-water, is compressed into 

 strong receivers. A company has been established at Paris for the 

 production of oxygen in this way, and it is expected that the gas 

 will be furnished so cheaply that it may be employed in the com- 

 bustion of the ordinary gases for illumination, so as to render their 

 light fifty per cent, cheaper, and at the same time get rid of certain 

 inconveniences which necessarily arise from the mode in which they 

 are burned at present. 



New Method oe Engraving. — The process devised by M. Comte 

 for this purpose consists in coating a plate of zinc with a white 

 water-colour, then drawing the design upon this with a fine point, 

 so as to uncover the surface of the metal, afterwards applying a 

 varnish which adheres to the plate only in those places which have 

 been laid bare by the point, and then washing off the paint with 

 water. The plate is next acted on with nitric acid, which forms 

 hollows between the lines produced by the varnish ; and thus there 

 results an engraving in relief, from which impressions may be taken in 

 the same way as from wood. This method gives the design actually 

 drawn by the artist, requiring no intermediate hand, which, how- 

 ever skilful, may be incapable of faithfully rendering the intended 

 effect. 



Cure op Consumption. — Any means of curing this insidious and 

 fatal malady must be hailed as a benefit of no ordinary value to the 

 human race. A remedy which is stated to have this effect was 

 brought before the Academy of Sciences, on the 12th of June. Raw 

 beef or mutton is reduced to a pulp in a mortar, and afterwards 

 passed through a sieve, to separate any tendinous matter. It is 

 then made into balls, which are to be rolled in sugar, or it is merely 

 sweetened with sugar, and administered in spoonfuls, to the amount 

 of from one to three hundred grammes daily. The patient must 

 use as a drink about one hundred grammes of the pulp diffused 

 through five hundred grammes of water sweetened with sugar ; also 

 three hundred grammes of sweetened water, to which one hundred 

 grammes of alcohol at 20° Baume have been added, are to be taken 



