348 Chemical Contributions. 



little or no danger of breaking it, when connecting it with other pie- 

 ces of apparatus. 3. That whereas Welther's tube projects far 

 above the apparatus to which it is attached, and is constantly in the 

 way, and in danger of being broken on that account : this is included 

 within, without however at all interfering with, or preventing the suc- 

 cess of the process that is going on ; or contaminating the substances 

 that are there. In the case of hydrogen, it is not necessary that the 

 funnel should rise at all above the nozle of the bottle. It has also an 

 advantage in procuring the gases, over a simple funnel with a long 

 stem, reaching very nearly to the bottom of the bottle, and dipping 

 into the fluid that is introduced, such as is recommended by Orfila, 

 and figured in his chemistry — ^because with that some of the gas gen- 

 erated will escape into the room. If any chemist should dislike the 

 trouble of making the instrument here proposed, himself, it is obvious 

 that the glass blower may take the business off his hands ; that the 

 tube may in fact be made so as to constitute but a single piece, and 

 ground into the botde, before it comes to the laboratory. 



When a two necked bottle is not at hand, a common gas bottle with 

 an orifice an inch across, will answer the purpose very well. Two 

 tubes pass through the same cork as is represented in Fig. 5, (the 

 cork itself being inclosed in a glass jacket that is ground into the bot- 

 tle, after the manner described in the note,) one for the conveyance 

 of the gas that is generated — the other receiving a small funnel into 

 its top, and entering itself through a cork into a test tube, having a 

 hole cut in its side and performing the office of a tube of safety. 



A tube of the kind here proposed, the funnel only being omitted, 

 may be ground into the middle orifice of a set of Woulfe's bottles, or 

 into the tubulure of the retort, when the gas that is passing through 

 them is generated and answers every purpose of Welther's tube of 

 safety, besides having some advantages over it. For it is evident that 

 it need not project at all above the apparatus with which it is con- 

 nected, and that if the diameter of the interior tube be small with 

 regard to that of the exterior, (and it is quite unnecessary that it 

 should be large,) the included gas may be safely kept under a pres- 

 sure of some half dozen inches of mercury, and the absorption in this 

 way promoted. Of its other applications I will notice but a single 

 one. Dr. Marcet's fine instrument for experiments on high steam, fig- 

 ured in the supplementary volume of the Philadelphia edition of Hen- 

 ry's chemistry, and ir Brande, is now very well made in New York, 

 and uppn the plan there exhibited, except that instead of two heniis- 



