566 

cools down the burning mass, and itself becomes 
heated in the process, whilst the carbon dioxide 
expelled from the water by the heat displaces 
the atmospheric oxygen in the immediate neigh- 
bourhood, and both causes combine to stop the 
combustion. The larger extinguishers such as 
are usually supplied to public buildings are of this 
kind. They contain, typically, a strong solution 
of sodium carbonate and a charge of hydrochloric 
or sulphuric acid. The acid is kept separated 
from the carbonate until the apparatus is wanted 
for use, when by means of a breaking or over- 
turning device the acid is mixed with the solution, 
and immediately liberates the carbon dioxide. 
The pressure of the gas forces the solution out 
of the apparatus, just as in the action of an 
ordinary “‘syphon”’ of soda-water. 
Other aqueous solutions, frequently used in 
small extinguishers of the hand grenade type, 
contain chlorides instead of carbon dioxide. 
Apart from the water, these are considered to 
act as fire-quenchers partly by producing extinc- 
tive gases, and partly by coating the burning 
material with a non-combustible film. One 
formula for such a grenade, for instance, contains 
common salt and sal-ammoniac, another includes 
calcium and sodium chlorides, others contain 
chlorides of calcium and magnesium. Of similar 
type, too, are some preparations containing 
sulphites. Thus a solution of sodium sulphite 
and sal-ammoniac acts as a_ fire-extinguisher 
partly by giving off ammonia and sulphur dioxide, 
partly by the cooling effect of the water, and 
partly by coating the burning material with sodium 
chloride. 
Of these small extinguishers it may be said 
in general that for quenching incipient small fires 
indoors they are useful, but too much should not 
be expected of them. The quantity of solution 
in a single extinguisher, or in half a dozen, is 
too small to be effective unless the fire is of quite 
restricted dimensions. Much of the quenching 
effect, it must be borne in mind, is due to the 
water; and though the chemicals enhance this 
effect, they do not multiply it to an unlimited 
degree. 
For use more particularly in putting out fires 
of burning liquids such as petrol, kerosene, and 
other mineral and vegetable oils, which float upon 
the surface of water and so may be spread by the 
latter, extinguishers containing dry powders are 
sold, and also others composed of non-aqueous 
“ 
liquids. The powders generally include carbon- 
ates or bicarbonates, with or without an 
admixture of chlorides. One much advertised 
article, for example, consists of a mixture of 
calcium carbonate and sodium bicarbonate. Their 
action depends chiefly upon the evolution of carbon 
dioxide and other gases, under the influence of 
heat. Like the hand grenade class, these 
extinguishers are in general effective only with 
small fires, and not in all circumstances. For 
example, a film of burning liquid might be 
extinguished readily by a covering of one of these 
powders, whereas the powder thrown on a thick 
NO. 2386, VOL. 95] 
NATURE 



[JuLy 22, 191s 

layer of the liquid might fall to the bottom and 
remain practically unaffected, at least until the 
oil had burnt down to its level. 
Of the non-aqueous liquids employed the chief 
appear to be chlorinated hydrocarbons. They are 
probably mixtures of several members, but 
approximate more or less closely to tetra- 
chloroethane, or to mixtures of this with carbon 
tetrachloride. These depend for their effect upon 
the production of extinctive gases when heated, 
and one disadvantage of their employment is the 
evolution of fumes, copious and unpleasant, con- 
sisting of hydrogen chloride. For use on small 
petrol fires, and also on small quantities of ignited 
inflammable materials, such as celluloid and 
carbon bisulphide, they appear to be reasonably 
efficacious. For larger fires, especially of loose 
combustible substances such as straw, paper, 
shavings, and the like, they are of much less value. 
‘Extinguishers of this class have thus a special and 
limited usefulness rather than general applicability 
to ordinary conflagrations. In fact with these as 
with all extinguishers, it is well to remember that 
whilst the prompt application to a small incipient 
fire may be effective, it is quite another matter 
when a big blaze has been allowed to develop. 
THE SURGERY OF THE WAR. 

Wye are familiar, by this time, with the saying 
that the War has brought “Listerism ” 
back for the treatment of our wounded. Not that 
the use of antiseptics had ever vanished out of 
practice : but the aseptic method—the sterilising, 
by heat, of almost every appliance of surgery— 
had come into general use, and had been reckoned 
as a great improvement on the antiseptic method. 
It had seemed a safer, more natural, more scientific 
way of operating. And in civil practice it is, 
indeed, well-nigh perfect. Itis ‘the ideal method.” 
That is to say, it would be perfect if all surgeons, 
nurses, and patients were perfect. But it is not so 
simple as it sounds: and some surgeons, perhaps, 
have so admired the pursuit of the ideal that they 
have been tempted to think of Lister’s work as a 
mere ‘“‘stage’”’ on the way to their own. Then 
came the War; and, at once, surgeons had to face 
a condition of wounds very different from the 
clean-cut incisions made in the formal operations 
at placid, well-appointed hospitals and nursing- 
homes over here. This overwhelming multitude of 
shell-wounds and shrapnel-wounds, infected right 
away with mud and sweat and particles of cloth- 
ing, and with all the germs of heavily manured 
soil, must be disinfected, if that were possible, 
with antiseptics. Thus, there has been that re- 
turn to the antiseptic method which Sir Rickman 
Godlee described, a few months ago, in his lecture 
at the Royal Institution. 
But this return to Listerism reminds us of Mme. 
de Staél’s wise saying, “L’esprit humain fait 
progrés toujours, mais c’est progrés en spirale.” 
If we are indeed back at Lister, we are back at a 
higher level. It is exactly half-a-century since he, 
in Glasgow, in 1865, first plugged the wound of 


