Comparative Atinlyfes of-Gunu and Sugar. 407 



. Now, an ounce meafure of carbonic actd gas weighs .864. of a grain, and this containt 

 .24 of pure charcoal : hence the quantity of charcoal to hydrogen in this inflammable gas 

 muft be as .24 to .048, or 5 to i. ' . ■ ' 



But one meafure of pure hydro-carbonate, fuch as may be obtained from the decompo- 

 fition of camphor, by making its vapour pafs through a red-hot earthen tube, or from the 

 diftillation of animal fubftances, opium, &c. requires two of pure air to faturate it J an4 

 the quantity of carbonic acid amounts to 1.45, which makes the proportion of carbon to 

 hydrogen as 12 or 1 3 to i. Hence thefe gafes differ materially, and ought not to be con- 

 founded : indeed, the difference between them is manifeft, from the mau^ner in which they 

 burn when mixed with common air, and brought into contadl with an ignited body. Pure 

 hydro-carbonate burns flowly, with a perfe£lly white flame, and never detonates : on the 

 contrary, the compound inflammable gas juft mentioned burns rapidly, with a reddifh 

 blue flame, and more or lefs of a detonation. We thought it necefTary to mention this 

 clrcuraflance, as much qonfufion might be produced by applying the fame name to fub- 

 ftances confiderably dilTerent. It is remarkable that a;ther, decompofed by heat, afFordi 

 pure hydro-carbonate, whilft alcohol yields the mixed fpecies. 



But to return : — An ounce of gum tragacanth was fubmitted In a coated glafs retort to 



a fimilar procefs, and the products collefted were as follows : 



dr. gr. 

 Charcoal remaining in the retort, - - - i 45 



Pyromucous acid, - - , - _ _ 4 5 



Carbonic acid gas, - - - - 78 oz. meaC. 



Hydro-carbonate, - - - - 91 ditto. 



The charcoal burned flowly with a peculiar phofphorefcent flame, and left a white rc- 

 Cduum of 12 grains, which was found to confift of lime mixed with a little calcareoui 

 phofphatc. 



The pyromucous acid being fuper-faturated with lime, the quantity of ammonia difcn- 

 gaged appeared to be confiderably greater than from that afforded by the gum arable. 



Having In this way difcovered lime in both fpecies of gum, we were anxious to know if 

 Ais earth could be detedled by reagents, without having recourfe to decompofition by heat. 

 Accordingly, a quantity of fulphuric acid was dropped into a folution of gum arable : after 

 {landing for fome hours, a number of needle-like cryftals were flowly depofited : thefe be- 

 ing feparated were difl"olved in diftlUed water ; to this folution the oxalate of ammonia was 

 added, when a copious precipitate of oxalate of lime Immediately took place. 



From thefe experiments, therefore, it is manifeft, that gums confiit of oxygen, hydro- 

 gen, carbon, azote, and lime, with a little phofphoric acid. 



An ounce of refined fugar was next introduced Into a coated retort, and the pneumato- 

 chemical apparatus applied, as in the former experiments. The products obtained were, 



oz. dr. gr. 



Pyromucous acid, with a drop or two of empyreumatic oil, o 4 30 

 Charcoal, - - - - - -020 



Hydro-carbonate, - - . . . 1190Z. meaf. 



Carbonic acid, - - - . - 41 ditto. 



The pyromucous acid being fuperfaturated with lime, not the leaft veftige of ammonl^' 

 could be -perceived. Sugaf, therefore, does not contain azote ; ncithtr does it coiitala IimeV 



3 G 2 for 



