568 TESTS FOR IMPORTANT MEDICINAL PREPARATIONS. 
While as a consequence the preparation to which it belongs, 
from a failure to meet the proper indications to its use, is 
become a stimulant, and slowly going out of use. 
Spirit of nitric ether . — Two or three fluid drachms of good 
sweet spirit of nitre that is not more than seven or eight 
months old, and kept in the usual way, contained in an ordi- 
nary test-tube, and plunged into water that has been pre- 
viously heated to 164°, will boil pretty actively. While, if 
freshly made, or not more than two months old, or if well 
preserved from light and air, no matter what the age, it will 
boil actively when surrounded with water at a temperature of 
156°. From the fact that this among other liquids may be 
heated far above its boiling point without ebullition, it 
becomes necessary to drop a few small fragments of broken 
glass into the test-tube with the spirit after the latter has 
been heated, and while still held in the water. Another 
precaution necessary in the application of this test, is to 
discriminate between the mere formation of small gas bubbles 
around the fragments of glass, and a true ebullition. For 
whilst the former will occur as a fine effervescence, at any 
temperature above 140° in any spirit of nitre that contains 
hyponitrous ether at all, true ebullition, in which the vapour 
bubbles are much larger and in which they reach the surface, 
and form, by their succession, a bead around the edge of the 
liquid, only occurs at the boiling points named. The prepa- 
ration should not be quite colourless, but of a pale straw 
tint, and should effervesce very slightly upon the addition of 
carbonate of ammonia. When slightly acid, carbonate of 
ammonia is the best corregent, because the salts formed are 
therapeutically similar. The officinal preparation is a solu- 
tion of 5 per cent, of hyponitrous ether in alcohol. The 
ether is the medicinal agent, and the alcohol is necessary for 
its preservation and dilution only, the latter indeed being 
often contra-indicated, as in some febrile conditions, where 
the former would be useful. In commerce, however, it is 
rare to find the proportion of the hyponitrous ether exceed 
3 per cent. W 7 hile in a great majority of cases it is below 2 
per cent., and often in a proportion too small to be detected 
except by the odour. One of the largest manufacturers in 
the United States makes it of five different qualities to suit 
the market, and all these below the officinal standard. 
Another maker (and the two produce a very large proportion 
of all that is sold in the United States), sells but one kind, 
and that, though of varying strength, is commonly below 2 
per cent. The above test alone will reject all such specimens. 
It thus happens that the physician who prescribes this pre- 
