Dr Marcefs Etxperiments on Sea-Water, 363 
General Observations. 
In the above experiments, the residues were dried as follows, 
viz. The residue obtained from the water by evaporation, was 
thoroughly dried at a boiling heat in a water-bath, till it entire- 
ly ceased to lose weight. The muriate of silver was heated to 
incipient fusion ; the sulphate of barytes and oxalate of lime 
were dried at a boiling heat ; and the ammoniaco-phosphate of 
magnesia, was heated to redness. No filters were used. The 
precipitates were washed, dried, and weighed, in the same glass 
capsules in which they were formed, with the exception of the 
magnesian salt, which was heated to redness by means of the 
blowpipe, in a very thin and small platina crucible. 
Art. XXVIII. — On the Formation of Sugar from the Sawings 
qfWood^ Old Linen and Paper. -By M. Biiaconnot. 
Our chemical readers are no doubt well aware of the inte- 
resting experiments of M. KircholF, a Russian chemist, by 
which he discovered that starch may be converted into sugar, 
possessing all the properties of sugar from grapes, by mixing it 
with about four times its weight of water, and about one 
hundred part of its weight of sulphuric acid This discovery 
was confirmed by M. Theodore de Saussure, who ascertained 
that 100 parts, of starch became 110.14 parts when turned into 
sugar. 
The same subject has been successfully resumed by M. 
Braconnot, who has discovered the important fact, that a sugar 
similar to that of grapes may be obtained by means of sulphuric 
acid, from the sawings of wood, and from old linen. 
In this operation, a certain quantity of these substances are 
treated with sulphuric acid, concentrated by cold. The mass 
appears to be carbonised, but this appearance arises from a 
* KirchofF also found that some other acids had the same effect. See Journal 
de Physique, tom. Ixxiv. 
