55 2 Progress in Science. [October, 



the Atomic. ,? Clinton Roosevelt. Subje&s connected with geology and natural 

 history formed the bulk of the papers. 



At one of the " Public Conferences ' ? of the French Association for the 

 Advancement of the Sciences, which was also held in August, at Lyons, 

 M. A. Gaudry delivered a lecture on the modern progress of chemical industry. 

 He informed his audience that the amount of sulphuric acid manufactured 

 annually in Europe amounts to 800,000,000 kilos., and would fill a canal 

 2 metres deep, 10 wide, and 25 to 30 kilometres in length. To yield this acid 

 800,000 tons of pyrites are yearly consumed. The condensation of the hydro- 

 chloric acid liberated in alkali works, the improvements of Mr. "Weldon and 

 Mr. Deacon in the manufacture of chlorine, the revolving soda-furnace, the 

 extraction of potash as a secondary product in the manufacture of beet-root 

 sugar, and the recent improvements in producing paper-pulp from wood, are 

 among the principal points touched on in the remainder of this popular and 

 able lecture. 



M. Ruimet des Taillis, writing in the " Chronique de la Societe d'Accli- 

 matation," states that, by feeding silkworms on vine leaves, he has obtained 

 cocoons of a magnificent red, and, by employing lettuce, others of a deep 

 emerald-green. M. Delidon de Saint Gilles, of Vendee, has obtained silk of 

 a beautiful yellow, other samples of a fine green, and others again of a violet, 

 by feeding the silkworms on lettuce or on white nettle. He points out that 

 the silkworms must be fed on mulberry leaves when young, and supplied with 

 the vine, lettuce, or nettle leaves during the las: twenty iays of the larva-stage 

 of their life. 



For the preservation of gum arabic from mouldiness Hirschberg adds a 

 little sulphuric acid to the solution, and finds that the mixture retains its 

 adhesive property uninjured after the lapse of eighteen months. 



M. Ducrot has published an interesting paper on apparatus for heating 

 with hot air. From the theoretical point of view, the writer concludes that 

 the quantity of calories furnished by the same apparatus, acting under the 

 same conditions, is greater as the heated air issues at a lower temperature. 

 By the same conditions, he means a constant external temperature, same 

 quantity of fuel disposed in the same manner on the grating, burned in the 

 same time with equal quantities of air. There is, however, for a piece heated 

 with a given weight of fuel per hour, a maximum of temperature corresponding 

 to a determinate quantity of air passing over the heating apparatus. 



The following process was proposed by the late Professor Fuchs for fastening 

 leather upon metal :— One part of crushed nutgalls is digested six hours with 

 eight parts distilled water, and strained. Glue is macerated in its own weight 

 of water for twenty-four hours, and then dissolved. The warm infusion of 

 galls is spread upon the leather, the glue solution upon the roughened surface 

 of the warm metal, the moist leather is pressed upon it and then dried, when 

 it adheres so that it cannot be removed without tearing. 



Steam has been proposed for extinguishing fires, by means of large pipes, 

 communicating with a boiler, and capable of filling the building with steam 

 in case of a conflagration. 



In a paper on the spontaneous combustion of hay, H. Ranke says that, 

 in consequence of prolonged fermentation, hay can become transformed into 

 a true coal, which, when exposed to the air at somewhat elevated temperatures, 

 acts as a pyrophorus. 



M. Jobert has instituted researches on the history of digestion in birds : he 

 finds that the gizzard is not exclusively a triturating organ, but a chemical 

 stomach, which secretes an acid liquid. 



According to E. Brescius beer may be clarified by means of tannin. For 

 1000 litres the author employs about 140 grms. of tannin, dissolved in 0-75 

 litre of water, which is thoroughly stirred up. After three or four days he 

 adds 1 litre of isinglass or 2 of gelatine in the proportion of 1 kilo, to 100 litres. 

 The complete clarification requires about eight days. 



