224 ANNUAL OF SCIENTIFIC DISCOVERY. 



ma\' be readily and economically effected by forcing tliiough 

 th'Mii when in the state of fusion a Jet of steam; chlorhydric acid 

 is formed together witii caustic alkali, or, if a stream of carbonic 

 acid be introduced with tiie steam, the carbonated alkali re- 

 mains. — Moii. Sci. No. 165. 



Extraction of Zinc from its Ores in the Wet Way. — Owing to the 

 scarcity of fuel, ami to the fact that the main bulk of the zinc ores 

 now obtained in Silesia contain only from 7 to 10 i)er cent, of 

 metal, experiments have been tried with a view of devising a 

 process for extracting the metal in the wet waj^ Ammonia-water, 

 chloride of ammonium, and hydrochloric acid were tried, but did 

 not answer the purpose. Chloride of calcium was then tried, and 

 found to answer well, even when the percentage of metal was as 

 low as 4 ; a nearly concentrated solution of chloride of calcium 

 and a boiling heat are required, and the process is less expen- 

 sive than the ordinary method of extraction by the dry way, and 

 the material obtained is readily reduced by the common method 

 of zinc smelting. The ore operated upon is an impure carbon- 

 ate of zinc. — Journ.f. Prak. Ch. 



Welding Copper. — The great obstacle hitherto experienced in 

 welding copper is that the oxide formed is not fusiljle. Rust 

 has found that the use of microcosmic salt gives a fusible slag. 

 This salt being expensive, he has substituted a mixture of one 

 part phos])hate of soda and two parts borax, and linds that it 

 answers the purjjose very well, although the slag formed is not 

 so fusible as that formed by the microcosmic salt. — Dingl. Pol. 

 Jotirn. 



Welding Compound. — An improved compound for welding has 

 been recently introduced in Belgium. It consists of iron lilings 

 1,000 parts, borax oOO oarts, resinous oil 50 parts, and sal-ammo- 

 niac 75 parts. The materials are mixed, heated, and pow- 

 dered ; the surfaces to be welded are dusted over with the com- 

 position and then brought to a cherry-red heat, at which the 

 powder melts, when the ])ortions to be united are taken from 

 the fire and joined. Another composition for the same object 

 consists of 15 parts of borax, two parts of sal-ammoniac, and two 

 parts of cyanide of potassium. These constituents are dissolved 

 in water, and the water itself afterwards evai)orated at a low 

 tem])erature. — Druggists'' Circular. 



Blackening Zinc. — Zinc may be given a fine black color by 

 cleaning with dilute sulphuric acid and sand, and then immersing 

 for an instant in a solution of 4 parts of suli)liatc of nickel and 

 amnion iinn in 40 parts of water acidulated with one part sul- 

 phuric acid. After washing and drying, there remains a black 

 coating, which adheres firmly, and takes a bronze color under the 

 burnisher. Brass may be stained black with a liquid containing 

 two pts. arsenious acid, 4 pts. hydrochloric acid, one pt. sulphu- 

 ric acid and 80 pts. water. — Ch. News. 



Tinning hg the Moist Way. — It is a well-known fact that, when 

 it is desirable to cover metals, especially brass or copper, with a 

 strongly adhering coating of tin, this is usually effected i)y boil- 

 ing the articles to be thus coated with an aqueous fluid, to which 



