242 On the Cause of the Collapse of a Reservoir. 
vessel BB. The cavity of the receiver should likewise be occupied 
by a freezing mixture. 
Into each of the remaining tubulures let a glass tube be introdu- 
ced, ground or luted to fit air tight, and tapering so as to terminate 
in a capillary perforation near the bottom of the bottle. 
Through one of the tubes introduce as much alcohol as will cover 
the bottom of the bottle, and then, by means of the other tube, in- 
troduce as much strong nitric acid as will cause an effervescence. 
Should the effervescence threaten to become explosive, the reaction 
may be checked by the further addition of alcohol, and when the 
reaction appears to decline too much, it may be re-excited by an 
additional quantity of acid. By these means, without applying heat, 
a quantity of nitric* ether will soon be condensed in the refrigerated 
bottle. To convert this ether into a liquid, fully equal to the offi- 
cinal sweet spirits of nitre, let it be mingled with seven parts of alco- 
hol and four of water. 
The colder the freezing mixture, the greater will be the product ; 
yet more or less may be obtained by refrigeration with cold water. 
It may be proper to mention, that at the bottom of the phial an 
aqueous acid liquor is deposited, upon which the ether swims, and 
from which it should be carefully separated. 
Arr. VI.—On the Cause of the Collapse of a Reservoir while ap- 
parently subjected within to great Pressure from a Head of Wa- 
ter; by R. Hars, M. D., &c. &e. 
From the Transactions of the American Philosophical Society. 
In September, 1834, I was requested-by Mr. Haydock, a respec- 
table and intelligent plumber of this city, to call at his shop in order 
to see a copper reservoir, which had collapsed while apparently sub- 
jected to internal pressure, arising from a communication with the 
mains proceeding from the public water-works. 
For the purpose of refrigerating the contents, the reservoir was 
placed in spring water, at the bottom of a well, so as to be at a small 
depth below the surface ; receiving the river water by one pipe, it 
was made to deliver it by another. 
The pressure of the water with which the city of Philadelphia is 
supplied, is known to be sufficient, when at its maximum, to com- 
* The proper appellation of this ether being unsettled, I adhere to that generally 
used. 
