272 ANNUAL OF SCIENTIFIC DISCOVERY. 



state, is that known as " chewing tobacco; " and a vast consumption of tin- 

 foil arises from this requirement of the tobacco chewers. I have repeatedly 

 prepared small quantities of chewing tobacco (the variety called " fine-cut' ') 

 for persons addicted to its use, by admixture with a little glycerine, and 

 always very much to their satisfaction. In the preparation of this drug, the 

 manufacturer must also please the palate of the consumer by introducing 

 some dulcifying ingredient. Common sugar or molasses, however, will not 

 answer the purpose, because they render the mass liable to ferment and turn 

 sour. An infusion of the root or extract of liquorice is therefore usually 

 resorted to. This does not, however, keep the tobacco moist, as molasses 

 would do; and to attain this it is necessary to press into solid compact masses 

 and pack into tight cases; or, in the case of the finer qualities, to enclose in 

 wrappers of tin-foil. In view of these facts, glycerine will be seen to supply 

 every requirement of the tobacconist, as it will not only keep his product 

 moist for an indefinite time, even when exposed to the air, but will also 

 sweeten it. He may almost look upon glycerine as made specially for his 

 use. 



The common water meters, used for measuring the consumption of illumi- 

 nating gas in houses, are open to two strong objections, namely: when in a 

 warm situation the water rapidly evaporates, and when in a cold place it 

 freezes. To avoid congelation, the usual expedient is to fill the meter, in cold 

 weather, with alcohol or whiskey, thus rendering the first-mentioned difficulty, 

 that of evaporation, still more inevitable. 



Now, what liquid do we possess which is practically free from both these 

 objections of evaporation and congelation? Evidently diluted glycerine. I 

 propose, therefore, as a substitute for both water and alcohol, for filling gas 

 meters, glycerine (sufficiently diluted to prevent its absorption of more water 

 from the gas, and increasing in volume to any important extent), thus ren- 

 dering the meter independent of attention within the ordinary limits of 

 temperature. 



For lubricating the bearings of fine machinery also, and particularly of 

 chronometers, glycerine seems to me worthy of a trial, as it is unchangeable 

 by the atmosphere, and remains at temperatures which few or none of the 

 oils will resist. For chronometers, pure oleine and oleic acid have been used; 

 but the former thickens on exposure to the air, and the latter congeals at a 

 few degrees below the freezing-point of water. 



Other uses occur to me, such as in the preparation of copying ink, in water- 

 color painting, and in the preservation of dried plants for herbaria in a flexible 

 state; mere allusions to which may at present be sufficient. 



CHEMICAL CHARACTERISTICS OF PURE GLYCERINE. 



According to Dr. Cap, pure glycerine, suitable for medicinal purposes, 

 should have the following properties: It should be odorless, even when 

 rubbed between the hands ; its consistency must be that of thick syrup. It 

 must be of honey-like taste, strongly sweet, its reaction nearly neutral ; one 

 volume of glycerine must be perfectly soluble in one volume of alcohol, acid- 

 ulated with 1-100 of sulphuric acid, without forming a deposit, when stand- 

 ing in a cool place, even after twelve hours. Further: one volume of gly- 

 cerine must dissolve in a mixture of 100-00 alcohol and 50-00 of sulphuric 

 acid, without forming a precipitate (salts of lime), or leaving syrupy residua 

 (adulteration with honey or simple syrup). In this way an addition of 10-00 



