( 164 ) 



and the manipulation much easier. These compressors are made very 

 carefully by the Burckhardt company at Basel. 



In the first compressor (© PI. II, displacing 20 M' per hour) the 

 gas is raised in the first cylinder (double-acting with slide) from 

 1 to 5 and in the second cylinder (plunger and valves) from 5 to 25 

 atmospheres; in the second compressor Sp (plunger and valves) in 

 the first cylinder from 25 to 50 and in the second from 50 to 250 

 atmospheres. After each compression the gas is led through a cooling 

 spiral. With the tw^o first cooling spirals (those of © PL II) an oil- 

 separator is connected. 



Safety-valves lead from each reservoir back to the delivery; 

 moreover the packings are shut ofl* with oil-holders (Comm. N". 14 

 '94 and N". 83, PL VIII). The hydrogen that might escape from 

 the packing at Sp is collected. 



b. The high pressure compressor forces the hydrogen through two 

 steel drying tubes ^a and T}b filled with pieces of sodium hydroxide 

 (comp. § 2, i, and PL II), of which the first also acts like an air- 

 chamber for the regenerator spiral. As in all the operations the gas 

 (comp. c) originally is almost dry and comes only into contact with 

 oil, we need only now and then run off a small quantity of 

 concentrated sodium hydroxide solution. 



c. For the usual working the compressors sack the gas from 

 gasometers. If these should float on water the separation of the water 

 vapour, which is inevitably taken along by the large quantities of gas 

 displaced, which constantly come into contact with water, would give 

 rise to great difficulties in tlie compression. Therefore we have used 

 for this purpose two zinced gasometers, Gaz a and Gaz b, PL II, with 

 tinned welds (holding each 1 M.') floating upon oil ^), which formerly 

 (comp. Comm. N". 14, Dec. '94) have been arranged for collecting 

 ethylene ^). 



The cock Kpa {Kph) is immersed in oil; likewise the connection 

 of the glass tube, through which the oil of the gasholder can be 

 visibly sucked up till it is above the cock, with the cover are immersed 

 in oil. The India rubber outlet tube and the connection with the 



1) The drawing sufficiently represents the construction which has been followed 

 for economizing oil. The gasometers can be placed outside the laboratory and 

 therefore they are protected by a cover of galvanized iron and curtains of tarred 

 canvas, which can be drawn round them. 



~) Formerly it was of the utmost importance that ethylene could be kept pure 

 and dry in the gasometers. But now the purifying of ethylene through freezing in 

 liquid air (comp. Comm. N'\ 94e IX § 1) has become a very simple operation and 

 weldless reservoirs for the storage of the compressed gas are obtainable in all 

 dimensions. 



