120 PURIFIERS. 



Let the superintendent go (not send) and fill a bladder, furnished with a 

 stop-cock, full of gas from the main, before it enters the purifiers, and also 

 one from each separate purifier, and let the bladders be labelled ; with a camel- 

 hair pencil paint tbe square marked crude gas with the test solution, and force 

 the gas from the proper bladder upon it while wet ; the paper will immediately 

 be turned black : then paint the square marked 1st purifier, and force the gas 

 into it, and proceed in like manner with the two others : the paper in the 

 fourth square ought not to be discoloured. The squares must not be moist- 

 ened at once, because the first impure gas would in that case blacken them all. 



Were I to mention all the various contrivances for purifying gas, they alone 

 would fill a volume ; in many instances the simple alteration of the machine 

 an inch or two either in height or length, or the position in which it was placed, 

 has served to found a claim of improvement, the machine so constructed being 

 called by the name of its inventor. Cream-lime, or a solution between the 

 hydrate and the completely fluid, has been tried several times ; the gas was 

 found to be acted upon efficiently, and completely purified, but the vessels so 

 soon became clogged that they were laid aside. If, however, some simple 

 means were devised to keep the lime in a proper state, they would be found 

 more ceconomical than any other plan. Again, the purification has been at- 

 tempted by passing the gas through heated iron tubes ; the sulphuretted hy- 

 drogen, it is true, is got rid of by this means, but the carburetted hydrogen is 

 also resolved into its elements, and the gas rendered perfectly unfit for the 

 purposes of illumination. If charcoal is introduced into these tubes the sul- 

 phuretted hydrogen is converted into carburetted and hydrogen gases. The 

 carburetted hydrogen of the coal-gas is partly, though not entirely decom- 

 posed, and cyanogen, carbonic acid, and carbonic oxide, are formed abundantly. 

 It is a better process than the former, but still very imperfect, and attended 

 with expense, uncertainty, and trouble. 



The following observations of Mr. Brande will be found in the Trans- 

 actions of the Royal Society, vol. ex. p. 19 : 



" The readiness with which carburetted hydrogen is decomposed when passed through 

 red-hot tubes, appears to me to offer a solid objection to a mode of purifying gas which 

 has been proposed by Mr. G. H. Palmer, since it would deposit carbon, and consequently 

 sustain great loss in illuminating power : the object in view was probably to get rid of 

 the sulphuretted hydrogen, but neither is this to be attained." 



Mr. Alexander Croll, the superintendent of the Chartered Gas Company's 

 works at Brick Lane, has lately taken out a patent for freeing gas from its 



