Chemical Contributions. 345 
Arr. XL.—On a Substitute for Welther’s Tube of Safety, with No- 
tices of other subjects; by E. Mrrcwe.t, Professor of Chemistry, 
Mineralogy, &c. University of North Carolina. 
- Weruer’s tube of safety, including under this title the three- 
branched tube, with an uniform bore, as well as that furnished with a 
bulb, is a convenient piece of apparatus in many operations, but is 
not without its defects. 1. The three parallel branches make the 
upper part too heavy for the slender stem that is to support it. 
2. From its form it cannot be attached to the apparatus with which 
it is to be connected, without considerable danger of fracture. 
3. When the fluid is once set a running through it, the lower part 
sometimes acts as a syphon, and carries over more of the acid or 
other substance we are introducing, than was intended. 4. Unless 
the upper leg be made most inconveniently long, its insulating power 
is feeble. 5. For its size and simplicity it is a costly article. 
The remoteness of my situation from glass-houses:and other man- 
ufacturing establishments, makes it quite impossible for me to get 
any thing, that may have failed in the course of my experiments, re- 
placed within-a moderate time ; and it is therefore important for me 
to contrive such modifications of apparatus, as shall render me less 
dependent on distant artists. On an emergency of this kind, I fell 
upon the following substitute for Welther’s tube of safety, which I 
propose to such of the chemists, as may be placed in circumstan- 
‘ces similar to my own. It has this at least to recommend it, that 
it requires only the beak of a broken retort, 4 few inches of 
straight tube, a little emery, and such other articles, as are found in 
every laboratory, for its construction 5 and in regard to convenience, 
T have found it so much superior, in many eases, to Welther’s tube, 
that IT should retain it in any situation. ‘The mode of constructing it, 
will perhaps be best understood, from an account of the method of 
fitting up a two-necked bottle, for making hydrogen, nitric oxide, 
carbonic acid, and sulphuretted hydrogen gases. 
L o 43 
Ore 
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Vou. XVIL—No. 2. 
