CHEMICAL SCIENCE. 247 



perature the less gas and the more liquid produced, and the higher the 

 temperature, the larger the volume of gas. An invention recently patented 

 b} T Stephen Meredith of Meadville, Pa., has for its object the facilitation of 

 the process of distillation, and this is accomplished by the admission to the 

 retorts, during the distilling operation, of a jet of heated hydrogen gas. In 

 this way the liquids are distilled in an atmosphere of hydrogen, and thus pre- 

 served from igneous decomposition, while the hydrogen at the same time takes 

 up a portion of the sulphur and ammonia contained hi the coal. 



PURIFICATION OF GAS. 



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A very great improvement in the purification of gas is claimed to have 

 been effected by Mr. Statter of England, by the employment of hydrated clay 

 along with the lime usually employed for this purpose. Hydrated clay unites 

 with the ammonia of the gas as with a base, and at the same time with its 

 sulphuret of carbon as with an acid, and thus removes both of these noxious 

 impurities from the gas exposed to its influence. Its good offices are, more- 

 over, said not to be limited to these, as, in conjunction with the lime, it assists 

 in removing tarry vapor and other impurities. The illuminating power of the 

 gas appears, from a detail of experiments, to be positively increased by the 

 clay purification from 22 to 33 J per cent. London Builder, No. 585. 



GAS FEOM PEAT. 



There has been much discussion hi Paris in connection with the renewal, 

 of the engagements of the city with the gas companies. Attention has been 

 called to the gas manufactured from peat, which for some time has been 

 manufactured in Paris. M. Foucault has been charged with measuring the 

 comparative illuminating powers of coal and peat gas ; and the result is hi 

 favor of that of peat, its power being 342, while that of coal gas is 100. 

 The manufacture of peat gas is also more simple than that of coal. The peat, 

 if put into an iron retort heated to a low red-heat, affords immediately a mixture 

 of permanent gases and vapors which condense into anoleaginous liquid, which 

 two products separate on cooling. The oil is collected hi a special vessel, 

 and the gas passes into a gasometer. This carbureted hydrogen is wholly 

 unfit for illumination, it giving a very small flame, nearly like that from brandy. 

 The oil from the peat is a viscous, blackish liquid, of a strong odor. It is 

 subject to a new distillation, and resolved wholly into a permanent gas and 

 hydrogen very richly carbureted. This mixture is strongly illuminating, giv- 

 ing a flame six or eight times brighter than the first, and of a more lively 

 brilliancy. The two are mixed, and a gas of intermediate character obtained, 

 which is delivered over for consumption. 



M. W)ucault has made his trials with a photometric method not yet made 

 public. Its unit was not a single wax candle, but a collection of seven can- 

 dles, arranged in an hexagonal manner, with spaces of one centimeter. A 

 single candle is liable to too much variation, a compensation for which is se- 

 cured when a number are employed. By this method, a mean of five deter- 



