1816. } during the Year 1815. / 47 
extricated; but the most curious and complete set of experiments 
on this subject are those of De Saussure, inserted in the last 
number of the Annals of Philosophy. He has shown that no 
gaseous products are exhaled; that the quantity of sulphuric 
acid is not altered; and that the weight of the sugar obtained is 
greater than that of the starch from which it was produced: hence 
he concludes that the sugar is merely a combination of the starch 
with water, and that the only use of the acid is to produce a solu- 
tion of the starch, in which state only it is capable of combining 
with water. 
Nasse has pointed out the differences between starch sugar and 
common sugar from the sugar cane. Starch sugar assumes the 
form of spherical crystals like honey. It is not so hard as common 
sugar. It is not sosoluble in water. Its sweetening power, ac- 
cording to the experiments of Kirchhoff, is to that of common 
sugar as 1 to 21. When digested with an alkaline carbonate a 
mucilaginous matter precipitates. This precipitate is obtained in 
greater abundance when the solution of starch sugar is mixed with 
muriate of tin. When dissolved in water it ferments of itself, 
without the addition of any yeast, which is not the case with com- 
mon sugar. (Schweigger’s Journal, vol. x. p. 305.) 
3. Extractive—A very long Paper has been recently published 
by Theodore Von Grotthuss (Schweigger’s Journal, vol. xiii. 
p- 117) containing experiments chemical and galvanic upon a 
great number of vegetable substances. It is not possible to give an 
abstract of it without taking up a great deal more room than I can 
at present spare ; but the object of the paper seems to be to show 
that the vegetable substance called saponaceous matter (seifenstoff’) 
by the Germans, is not the same with the extractive, as has been 
endeavoured to be proved by Fourcroy and by Schraader. As 
nobody has hitherto succeeded in obtaining either of these sub- 
stances in a pure state, such discussions do not seem susceptible of 
much precision. Grotthuss gives the following process for obtaining 
naceous matter in a state of purity. Boil together saponaria 
officinalis and quicklime in a sufficient quantity of water. Filter 
the liquid. Precipitate the lime by phosphoric acid. Filter and 
evaporate the liquid slowly to dryness. The residuum is pure 
saponaceous matter. 
4. Cinchona.—For the first set of experiments on the different 
kinds of Peruvian bark we are indebted to Vauquelin, who was, I 
believe, the first person who distinguished one of the constituents of 
that substance by the name of cinchonin. A Portuguese of the 
name of Gomes published a new set of experiments on this subject 
in the Edinburgh Medical and Surgical Journal (1811) and an- 
nounced the discovery of a new species of cinchonin, To verify 
this discovery, a set of experiments was made by Dr. Van Smissien, 
in Professor Pfaff’s laboratory at Keil, under the direction and by 
the assistance of the Professor. These constituted the subject of 
5 
