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~XXXVII. Further Observations on Mr. Luxson’s Safety 
Blowpipe Appendages. 
To Dr. Tilloch. \ 
Nottingham, Jan. 18, 1822. 
Sir, — see results of several experiments, made by me since 
I last addressed you, have induced me to make some alterations 
in my Safety Appendages, described in the 284th Number of 
your Magazine ; and my anxiety for the improvement of the 
blowpipe, added to a hope of exciting the attention of persons 
more qualified than myself to add to the resources of science, 
will I trust be a sufficient apology for my again troubling you. 
Instead of allowing the gas to enter through the sides of the 
safety cistern, as represented at H in the Plate accompanying 
my former paper, in Number for December, I cause it to enter 
through a hole drilled in the bottom of the cistern as represented 
at A, Plate III. fig. 4. The reason of my alteration is, that 
owing to the great cohesive attraction of mercury, if that be 
used to fill the safety cistern, the gas passes up the sides of 
the cistern instead of bubbling through the mereury; and when 
a continuous stream of gas is thus produced, an explosion will 
infallibly ensue if the gas within the safety cistern be ignited. 
When the gas enters through the bottom of the safety cistern, 
the apparatus is perfectly safe.—Fig. 4 is of the real size. 
I have found from experiment that the cane I mentioned is 
not safe, as the gases readily ignited through a piece one inch 
and a quarter in length. Wire-gauze is therefore preferable, and 
the small ledge in the lid of the safety cistern will serve to sup- 
port the pieces, which should be cut by a punch of a proper size, 
and introduced into the cylinder B_ before screwing the jet pipe 
in its place. 
Although I have purposely ignited the gas within the safety- 
cistern, I find the apparatus as it is now described perfectly safe 5 
nor does any injury result to the valve from the trifling expansion 
which then takes place. 
I have used the appendages without either cane or wire-gauze, 
and with a jet about an inch in length, the aperture of which 
tapered from 1-10th,to 1-30th of an inch in diameter with 
perfect safety. 
It is always better to examine the valve, after the gas within’ 
the safety-cistern is ignited, in order to remove any mercury that 
may have accidentally lodged therein. 
The valve I now use has no grooves on the top of the plug 5 
small plate being screwed on the bottom of the spindle to pre- 
vent the plug from rising too high. 
I have frequently exploded about two quarts of the mixed 
gases 
ee ee 
; 
sie 
