( 674 ) 



Ni'. 51, and shown in dolail in Hie above inonlioiiod desci-iplioii I.e. p, 

 38a Nr. 7). 



The hmji' |»in (see 1^1. I). A'„ riuis lirsl ihroiigli llic iidel tube 

 V/ coiitiinied bv X,, hti' the inellivkddoi'ich^ and is pressed asuiii.st 



"ill' .111 . 1 r^ 



\\\o ()]»(Miiiig' ill the boKom A\j ol' Ihe lul)e X/j^^^ by means of a 

 screw in A^^,,, al)ove tlio side inlet lnl)e N,.. for metiiyleliloride. The 

 Inbe with cock Xb rests loosel}' in the sjiecial tube /A;,. The joint 

 is closed by caontchonc J)e., on the enlaruenieni A\,., and allowance 

 is made in tliis manner for the relati\e slliftin<i- of the tubes owing' 

 to change of temj)eratiire. 



This arrangement is nsed when metiiyleliloride at the ordinary 

 temperature is admitted to the ajjparatns. 'I'lie cock AMnsnlated from 

 the tube Dc is l<e])t at the ordinary tempei'atiire by the thick iron 

 ring iSc i^Jid the caoutchouc at the njiper end thus remains soft 

 while otherwise having become i»rittle by cooling it would break 

 owing to the uneciiial displacement of X and JX. It is always neces- 

 sarv to introduce the metiiyleliloride ai (he oi'dinary temi)erature 

 A\ Ikmi it is not (piite pure and i\v\ \ otherwise the cock will be 

 frozen fast. A cock of the model A' is \-ery appr()])riated for the 

 admission of niethylchlorido at tlu^ ordinaiy tem|)eratin-e. 



A good nuMliod for pni-ifying the necessary (piantily of metiiyleliloride 

 consists in draw iiig (ill' iIk' iiiethy Ichloridc in the boiling vessel by means 

 of the cock A' and causing it to evaporate by condensing ethylene in 

 the spiral. If the cock freezes, Ihe pressure is made ecjual to that of 

 the atmos|)liere by shutting /. oil', or if Jiecessary bringing the ajipai-atiis 

 in coiiii(>elioii with the sacks .0 (1*1. 11.) ihroiigh A. A' can then be 

 taken oiil of /),. IJefore using the llask after a process of purilication 

 il is lirsl dried by the aid of the tube and c(tck 7',. 



If the inethylchloride is lirsl cooled by contact with a cold gas, 

 as is shown a! ^' on PI. II next to the principal drawing, the inlet 

 tube passes ihroiigh an ordinary cock A';. 



'J'lie cock 7'/, serves to introduce the ethylene to be condensed, the 

 cock 7',., which is placed on wood and jiacked in wool, to draw it oft'. 



The cock 7', is inserted in th(^ lube J/,, which runs to Ihe bottom 

 of the cylindrical s|»ace (' ami is used for cleaning and drying. 



The |»osilion of the li(piid metiiyleliloride can be seen from the 

 float J\. which moves u|) and down in the central tulie C ',., , itself 

 i]i connecliou with the space round the sjiiral through the lube 

 ( \i . \\\ iiKMus of an aluniinium wire, a silk vovd and a plalinum 

 wire, /\. is joined to a silk cord /-*,, which passes oxer Ihe [udley 

 Qi, into Ihe glass tube (l,, where il is attached to a weight /^, 

 which runs along a scale fixed to the lube (I,. 



