268 ANNUAL OF SCIENTIFIC DISCOVERY. 



ounces) of monohyclratcd nitric acid, previously immersed in a freezing mix- 

 ture. The temperature rises upon each addition. It is therefore necessary 

 to allow the mixture to cool down again to 10 C. (14 Fahr.) before any 

 fresh addition is made, as it is very necessary that the temperature should 

 never rise above C. (32 Fahr. ) When the glycerine and nitric acid have 

 formed a homogeneous fluid, which may be facilitated by stirring the mix- 

 ture with a glass rod, 200 cubic centim. (18 ounces) of concentrated sulphuric 

 acid are cautiously and slowly added. 



" This operation is accompanied with the greatest danger, if the tempera- 

 ture is not continually watched. Experience, however, shows me that there 

 is no reason for fear, provided the temperature be always kept below C. 

 (32 Fahr.) 



" When these precautions have been taken the nitro-glycerine separates, 

 after the addition of the sulphuric acid, in the form of an oily liquid floating 

 on the surface, and may be collected by means of a separating funnel. 



" The product thus obtained, which is still contaminated with a little acid, 

 weighs about 200 grammes (308f5.G grs.). A still further portion, however, 

 about 20 grammes (308.6 grs.), may be obtained from the acid liquor by dilut- 

 ing it with water. 



" The products thus obtained are then dissolved in a small quantity of 

 ether, and this solution repeatedly shaken with water, till all trace of acid is 

 removed. The ethereal solution is then heated over a water-bath till nothing 

 more is volatilized. 



" Properties. Nitro-glycerine is an oleagenous liquid of a clear yellow 

 color, having a sp. gr. from 1.595 to l.GOO. Heated to 160 C. (320 F.) it is 

 decomposed, evolving red vapors ; at a higher temperature it either explodes 

 or inflames without any detonation. 



" It is difficult to determine accurately the point at which explosion takes 

 place; it is best observed by allowing the nitro-glycerine to drop, from time 

 to time, upon a piece of heated porcelain. At first it burns away with a vivid 

 flame ; but as the temperature diminishes, it violently explodes, evolving red 

 vapors, and frequently breaking the porcelain on which it falls. 



" By placing a drop on an anvil, and striking it with a hammer, it instantly 

 detonates. When properly prepared, and free from acid, it may be kept for 

 any length of time. I have some in my possession, which has been kept for 

 two years without undergoing the slightest change. 



" Upon the addition of sulphuric acid to the ethereal solution, decomposi- 

 tion ensues, and a great quantity of sulphur is thrown down." 



The following is Mr. Field's description of his experience, of the effects of 

 glono'ine. 



" On the evening of the 3rd of February, 1858, 1 was conversing with a 

 homoeopathic practitioner, when he mentioned a medicine which possessed 

 peculiar and extraordinary qualities, some of which he described as having 

 affected himself, though he had taken it in very minute quantities. I 

 laughed at his credulity, and offered to take as much as he pleased, upon 

 which he let two drops of what he called the first dilution of glono'ine fall 

 on my tongue. After swallowing this small quantity of fluid I was as- 

 sured the quantity did not exceed two drops I asked what effects I must 

 expect, but was told to wait and observe for myself. I then purposely con- 

 versed on other subjects. In about three minutes, I experienced a sensation 

 of fulness in both sides of the neck; to this succeeded nausea; and I said, 

 ' I shall be sick/ The next sensation of which I was conscious, was as if 



