S84 Dr. Prout on the ultimate composition 
Manna Sugar. The saccharine principle existing in manna 
has been long known to possess peculiar properties. That 
employed in the following analysis was separated by means 
of alcohol in the manner commonly described in chemical 
books, and was obtained in a state of perfect purity by re- 
peated crystalizations from that fluid. It was then dried at 
2 1 2°, and in this state was found to consist of 
Carbon 38-7 
Water 61-3 
results very different from those of M. Theodore de Saus- 
sure.* This sugar seems to part with hygrometric water 
only at the temperature of boiling water ; but a few degrees 
above this point it begins to suffer decomposition, and at 250° 
it assumes, without melting, the form of a brown powder, and 
acquires a strong empyreumatic odour. 
Gum Arabic. A very fine specimen of gum arabic reduced 
to powder, and analysed as it existed under the ordinary 
circumstances of the atmosphere, was found (abstracting 
foreign matters ) to consist of 
Carbon 36*3 
Water 63-7. 
One hundred parts of the same gum, exposed to a tempe- 
rature between 200° and 212 0 , for upwards of 20 hours, lost 
12-4 parts. Hence its composition thus dried would be 
nearly Carbon 41 - 4 
Water 58 ' 6 . 
Results confirmed almost exactly by actual analysis. 
The same gum, further exposed to a temperature between 
300° and 350° for six hours longer, assumed a deep brown 
See Bibliotheque Britannique, 1814; also Annals of Philosophy, vi. 424. 
