326 Sctentific Intelligence. [ApRIL, 
ArticLe VIII. 
SCIENTIFIC INTELLIGENCE; AND NOTICES OF SUBJECTS 
CONNECTED WITH SCIENCE, 
I. Lectures. 
Dr. Merriman and Dr. Ley will recommence their lectures on 
Midwifery, and the Diseases of Women and Children, on Monday, 
April 21, at the Middlesex Hospital. 
Il. New Method of taking the Specific Gravity of Gases. 
(To Dr. Thomson.) 
SIR, 
Havine often been disappointed in procuring that degree of ex- 
haustion in a globe which is necessary for the weighing of different 
gases, a point of no inconsiderable moment with the practical 
chemist, in considering the subject, the following appeared to me 
an easy and expeditious method of forming (in my opinion) a most 
perfect vacuum, without that liability of iailure which is attendant 
upon the use of the air-pump, where you can seldom procure a 
sufficient degree of exhaustion for so delicate an experiment. 
The apparatus consists of a glass globe, a (Plate LXVI., Fig. 3), 
mounted with an iron stop-cock, , which by means of a screw is 
able to be fixed to the iron tube, c, also furnished with a stop-cock, 
d, at its upper end, which tube should be 32 inches long; e isa 
small glass funnel. 
Having placed the apparatus in the position, fig. 3, with the glass 
globe screwed to the tube, open the stop-cocks, and by means of 
the glass funnel, e, fill the globe and tube with quicksilver, remove 
the funnel, and turn the cocks. It may now be turned with the 
globe uppermost (Fig. 4) ; and if the mouth, d, be introduced under 
the surface of quicksilver in a proper vessel, and the stop-cocks 
opened, the quicksilver will descend, leaving the globe and part of 
the tube in a state of most perfect exhaustion; by fastening the 
cock, J, it may be removed from the tube for use. 
Should the above possess sufficient novelty and utility to merit a 
place in your Annals, you will oblige me by its insertion. 
Iam, Sir, yours truly, 
Barnet, Feb. 9, 1817. Tuomas S. Booru. 
Ill. Further Improvement in Brooke’s Blow-pipe. By Dr. Clarke. 
(To Dr, Thomson.) 
SIR, 
Dr. Wollaston having suggested the expediency of increasing the 
number of the tubes, rather than the diameter, for the jet of the 
gaseous blow-pipe, I have, in consequence, adopted a plan for 
