CHEMICAL AND PHYSICAL NOTES. 95 
For this purpose the supply of steam must be ample, while its means 
of escape into the atmosphere must be so free that no rise of pressure, 
due to over-supply of steam, can be produced. The steam, which is 
condensed on the walls of the steam tube, should run freely back into 
the flask without collecting at the bottom of the wide part of the steam 
tube. Therefore the tube making the connection with the boiling flask 
must be pretty wide; and the exit tube from the steam vessel must be 
a trifle wider still. Of the steam which enters the tube, part is con- 
densed on the walls and keeps them at constant temperature, and the 
remainder passes away in a stream of good 
volume through the exit tube. With very 
little attention to the construction and 
management of the apparatus, every risk of 
cooling from without or heating from within 
is completely avoided. 
Description of the Apparatus.—A. general 
view of the apparatus is seen in Fig. 1. It 
consists of four parts: the lamp A, the 
steam generator B, the steam vessel or 
distilling tube C, and the thermometer 
D. The lamp shown is one of a 
French pattern, sold with the Réchaud a 
double flamme forcée of smallest size. It 
holds about 250 c.c. of spirit, and gives a 
flame powerful enough to work a much 
larger flask. The steam generator B is a 
flask made of spun copper, and of 500 c.c. 
capacity. A suitable charge is 300 c.c. of 
water. With such a charge, and heated by 
the French lamp, the water boiled in six 
minutes at an expense of 12 grms. of spirit. 
While keeping steam at the rate suitable 
for the experiment the lamp consumed 21 germs. of spirit in fifteen 
minutes, and evaporated 92 grms. of water. It is obvious that 
where gas is available a gas lamp may be used. 
A very convenient lamp, especially for work out of doors, is 
the Swedish lamp for burning petroleum or paraffin oil under pressure, 
and with a blue flame. It is particularly useful when larger steam 
generators are used, such as the metal flasks made for the Napier’s 
coffee machines, used in restaurants. One of the ordinary size 
holds 2 litres, and is a most useful article both in the camp and the 
laboratory. 
Sat Ty 
wii 
