349 
IMPORTANT DISCOVERIES. 
It is well known, that the common beer 
pump, with a leaden pipe, has frequently 
given to the liquor a dangerous impregnation, 
especially after remaining stagnant for a time, 
and the beer in a sour state. The substitution 
of block tin would remove the apprehension 
of danger, but its greater price offers a strong 
temptation to the use of lead. It appears to 
me that the lead lube lined with tin will an- 
swer the ends of cheapness, safety, and 
durability. I would therefore invite your 
attention to the following experiments, which, 
if you think them of any importance to the 
public, you may insert in your Journal. 
Experiments . — Various portions of lead 
tube, coated, some with pure tin, and others 
with different alloys of tin and lead, were 
bent into the form of a semi-cii cle, and filled 
with vinegar of different degrees of strength. 
After standing, some a month, and others six 
weeks, with occasional disturbance, the clear 
solutions were tested, first with sulphate of 
soda, and afierwaids with bihydro-sulphuret 
of ammonia. The application of the first of 
these tests, namely sul. soda, produced no 
alteration in any of the solutions, from which 
it must be inferred that they contained no 
lead. 
The application of the second test produ- 
ced, as was anticipated, a brown precipitate 
of sulphuret of tin. In the same manner, 
two fresh pieces of tube were filled with a 
strong solution of common salt, which re- 
mained in contact for some time. The solu- 
tions, when assayed with the same tests, show- 
ed that notliing but a little tin was dis- 
solved. 
It appears that in all these cases, which I 
regard as galvanic effects, the tin was the most 
oxidahle metal, although, when not under the 
influence of polar arrangement and in the open 
air, lead appears to oxidiate sooner than tin. 
It is scarcely necessary to lemind you that re- 
sults similar to these were obtained thirty 
years ago by thecelebrated Professor Proust, 
at Madrid, who undertook for the Spanish 
Government an extensive seriesof experiments 
on the different alloys of lead and tin, with 
the express view of determining whether the 
popular prejudices against the coating of cop- 
per vessels with an alloy of tin and lead, 
which is the common practice, was ill or well 
founded. Nothing can be more satisfactory 
than the conclusions he drew from his labours, 
namely that as, in all his numerous experi- 
ments, neither lead nor copper were dissolved, 
there is little reason to fear the solution of 
lead from the tinning of our kitchen utensils. 
I may just mention here, that I am in the 
habit of cleaning out my soda fountain every 
spring with dilute muriatic acid, which uni- 
formly dissolves the oxide of tin without 
touching the copper, which 1 am persuaded 
will remain as securely as the sheathing cop- 
per in Sir Humphrey Davy’s great experi- 
ment, and for the same reason.— /Immcan 
Journal of Science and Arts, 
METHOD OF MAKING CAPILLARY 
TUBES IN METAL. 
For gas-burners, for the safe combustion of 
mixtures of oxygen and hydrogen, and forother 
purposes, it is often desirable to divide the 
end of the discharge-pipe into fine capillary 
tubes, of the depth of half an inch or more. 
It is difficult and expensive to bore such 
apertures ift a piece of solid metal, and it is 
hardly possible to he executed at all, if the 
apertures are required to be of very small 
diameter. 
Two new methods of producing such capil- 
lary tubes have been communicated to the 
Society of Arts — one by Mr. J. Roberts, of 
Queen-street, Cheapside, and the other by 
Mr. Henry Wilkinson, of Pall Mall — which 
are thus described in the last Part of the So- 
ciety’s Transactions: — 
Mr. Roberts’s Method. 
“ Mr, Roberts very ingeniously and expe- 
ditiously subdivides the end of a. metal pipe 
into small tubes of any required depth, by 
means of pinion-wire. Pinion-wire is made 
by taking a cylindrical wire of soft steel, and 
passing it through a draw-plate of such, a 
figure as to form on its surface deep grooves 
in the direction of radii to the axis of the 
wire: the ribs which separate these grooves 
from one another may be considered as leaves 
or teeth, and of such wire, when cut into pro- 
per lengths, are made the pinions used by 
watchmakers. Hence arises the name by 
which this wire is commonly known. If now 
a piece of this wire be driven into the end of 
a brass pipe of such a size as to make a close 
fit with it, it is evident that part of the 
pipe has thus been subdivided into as many 
smaller tubes as there are grooves in the wire. 
By using a draw-plate fitted to make smaller 
and shallower and more numerous giooves 
than are required in common pinion-wire, it 
is manifest that wires or cores may be pro- 
duced, which, when driven into metal pipes, 
as already described, will subdivide them into 
capillary tubes of almost any degree of 
tenuity.” 
Mr. Wilkinson’s Method. 
“ In the course of some experiments on 
artificial light, which I was enpged in about 
twelve months since, I was desirous of obtain- 
ing a great number of extremely minute aper- 
tures for a gas-burner ; and, finding it impos- 
sible, in the ordinary way, to obtain them, a 
new method occurred to me, which imme- 
diately produced the desired effect. I showed 
it at the lime to several eminent scientific 
men, who were unable to conceive how these 
apertures were formed; and, as I made no 
secret of the method, they were equally 
pleased at the simplicity of the operation ; 
and the specimen herewith sent has been ex- 
hibiting at the Gallery of Practical Science 
for several months. 1 did not attach much 
importance to it myself ; but, as 1 do not 
find that it is at all known, and now think it 
might be useful in a variety of ways, I have 
sent it for you to lay before the Society; and 
