Processes in the Useful Arts. lf>S 



where d represents the diameter of the orifice, h the height of the mano- 

 meter, b that of the barometer, and t that of the thermometer. 



From the experiments of M. D'Aubuisson which it is unnecessary to 

 repeat more particularly, it follows, — 



That the conical has little advantage over the cylindrical form of the 

 aperture, which is not the case with incompressible fluids. 



That when air issues from a reservoir under any pressure, the ratio be- 

 tween the real and the theoretic discharge will be 0.65 if the discharge is 

 made by an orifice pierced in a thin plate ; 0.93 if we employ a short cylin- 

 drical ajutage ; 0.95 if a short conical ajutage is used ; and, referring to the 

 case which is most interesting in practice, M. D'Aubuisson adds, t]»at, by 

 employing ajutages or bases slightly conical, the real will be six per cent, 

 less than the theoretical discharge. — Ann. de Chim. torn, xxxii. p. 327. 



3. Method of restoring Wine that has been turned. 



A method has been in practice for some years to restore wine that has 

 been turned. The process consists in adding from half an ounce to two 

 ounces of tartaric acid of the shops, to a hectolitre of wine, according 

 to its state of decomposition. The tartaric acid reproduces the tartar, dis- 

 engages the carbonic acid, and consequently destroys the alkaline charac- 

 ter given to the wine by the sub-carbonates. 



The Agricultural Society of Bourges has frequently repeated this ex- 

 periment ; but it has not always succeeded. They, however, ascribe this 

 uncertainty to the impossibility of determining the exact quantity for 

 every case. — Bull, des Sc. Technol. Sept. 1826. p. 145. 



•1. Method of preventing, by means of Galvanism, the formation of calca- 

 reous deposits in Leaden Pipes. By M. Dumas. 

 Most of the springs which rise in the hills in the neighbourhood of the 

 Seine are charged with carbonate of lime dissolved in carbonic acid. By 

 considering this product as a solution of the bi-carbonate of lime, M. 

 Dumas conceived the idea that it might be decomposed into carbonate, and 

 into acid by a weak galvanic pile. He found that the calcareous deposits 

 in leaden pipes were formed principally at the soldered joints, upon the 

 bars of iron and the copper cock which met at these places. He there- 

 fore placed a galvanic pair in a vessel filled with water from a spring 

 which supplied the manufactory at Sevres, and at the end of two days 

 the surface of the copper only was covered with a flocculent deposit. A 

 plate of silver, soldered to a bar of lead, was placed in a reservoir of the 

 same water, and at the end of six months the silver was found covered 

 with a thick stratum of deposit, whilst the lead was perfectly clean. M. 

 Dumas therefore proposes to prevent these calcareous deposits, by placing 

 at different distances along a leaden pipe, other small pipes, perpendicu- 

 lar to the first, and communicating with it, and into which might be in- 

 troduced at pleasure bars of iron, for the iron being more electro-nega- 

 tive than the lead, will have the calcareous deposit form :d upon it. — Bull, 

 des Sc. Technol. Sept. 1826. p. 155. . 



