On the prefent State of A'irojlation. 2r 



tally heavier than even common air. It muft be alfo totally 

 devoid of greafe, as the fmalleft ftratum of greafy matter will 

 effectually fecure the iron from being attacked by the acid. 



To 



trtme orifice be ('iminifted to an inch diameter*, and in fuch a dire£tion 

 as eafily to be placed under, and fix or eight inches below, the bafe of the 

 inverted funnel of the refervoir. iJefidcs this central tube there muft be 

 a lateral one of an inch diameter and fix inches in height, provided with 

 an air-tight wocden ftopper. Thiou^h the head muft alfo be fixed a glafs 

 or pewter tu!)e bent to form an inverted fyphon, the fhorter leg of which 

 muft be placed fo as to be included in the veffel, while the longer leg 

 (of two feet in length) will remain on the outfide. A third veffel muft 

 alfo be provided, as a refervoir or cooler, capable of holding from 200 to 

 300 gallons, open at top, yet not more than three feet deep. Acrois its 

 diameter, and eight or ten inches below its upper rim, fix two ftrong 

 wooden bars as fupports, to which tix an inverted wooden funnel (the 

 bafe of which muft not be lefs than tvo feet diameter) whofe upper part 

 fhould end in a tube, round which the varniflied filken tube immediately 

 connected with the balloon is to be faftened. After properly fixing the 

 inverted funnel, provide a fquare wooden tube, and fix it to the infide of 

 the refervoir fo as to reach within fix inches of its bottom, while its upper 

 orifice Ihould ftand at leaft a foot higher than the furface of the water 

 therein. This being done, and the extremities of the large tin tubes being 

 properly placed under the inverted funnel, begin with pouring feveral 

 gallons of cream of lime (made by flaking quicklime in water, a gallon of 

 fluid to two pounds of lime) into the refervoir; then gradually fill the 

 fame with water till within an inch or two of the top. In the next place, 

 pour through the inverted fyphon of each tub a mixture of one part acid 

 and fix of water, while an alfiftant ftanding over the fmall lateral tin tube 

 (now open) replaces the plug in the fame at foon as the fmcU of the hy- 

 drogen gas rs perceived, indicating that the atmofpheric air is now all ex- 

 pelled from the tub. And thus muft the workmen proceed, pouring the 

 diluted acid into the tubs through the fyphons till fuch time as the required 

 quantity for each veffel (/'. e. looo pounds of acid, and 6000 pounds, or 

 750 gallons, of water) has been added; the column of tiuid retained in 

 the fliorter leg of the fyphon forming a ftopper, whereby any efcape of g-is 

 at this aperture is prevented. 



A feparate alGftant muft in the mean time attend the pneumatic cooler 

 to renew the water therein, which will be at intervals faturated with all 

 the matter it can abforb from the gas; he muft therefore occafionally dif- 

 place this water by pouring freih quantities down the fquare wooden tube 

 for the purpofc, which will caufe the faturated tiuid to fiow over the top 

 of the veffel, and in doing the fame muft, for every frefh addiiion of water, 

 add i proportion:»te quantity of the cream of lime. During the whole of 

 the experiment the water in the cooler muft be ftirred with a wooden rod, 

 t'lat the unfaturatcd lime (continually tending to precipitate itfelf) may 

 be perpetuitlly brought into conta6t with the gas ; while, the more frequent 

 the lencwal of the water in the refervoir, and the larger the proportion of 

 frdfi cream of lime, the lighter will the gas be obtained. Alfo, to facili- 



• By this contrivance the gas will iffue in acontinucd ftream, which will 

 prevent that great agitation of the water under the funnel which is occa- 

 fioned by the gas forcing its way through the water in large quantities at 

 a time, yet at intervals of fome diftancc, whereby much of it i> frequently 

 loft. 



C 3 tate 



