1816.) during the Year 1815. 2h 
Twenty Grains concentrated Sulphuric Acid in two Ounces Water. 
Glass ......... 75°5 gts. Wangs. 03500, -. 79 grs. 
Sulphur ....... 75 Tatlow eo). 3562 OTF 
j MY, |S 
Concentrated Solution of Potash. 
PAIOE0:4.5ia'0, dd 9,0: 459,, COMETS. Tallow ....+..++ 66 grs, 
Sulphur......... 67 GasS, oo sin asaean 64 
RE: a> aun een 
The effect of the addition of a little acid or salt to water was 
remarkable. Two ounces of pure water were employed. Plates. 
of zinc and glass required the following weights to separate them 
from the liquid: 
Babi Cie. hi2 . 78 grs. | Glass ...... 76 grs. 
Six grains of concentrated nitric acid being added to the water, 
the weights required were as follows : 
ZANE oo see es £4 Bis. bis (PSS an teat g'n OS CTS 
In another experiment the weights necessary to separate the zine 
and glass from ‘aii water were as follows : 
Zine ....... 78 grs. | Glassiss))../.)F6:S.ere; 
Six grains of -eklawaved sulphuric acid heii added, the 
weights became 
ZMNC “oe e see GD Lis | GTA 6. ole. 9 FL BTS 
These are the principal experiments. I pass over some others, 
the chief object of which is to point out the errors liable to be 
committed in such experiments. 
4. Fermentation is one of those mysterious processes which 
chemistry has not yet been able to explain. On that account every 
fact relating to it is of importance; for it is only by an accumula- 
tion of facts that we can expect to throw light upon this obscure but 
most important process. I shall therefore state here the result of 
some experiments made upon yeast by Dobereiner. ‘They are not 
of much importance ; but still they are worth knowing, (Schweig- 
ger’s Journal, xii. 229.) He obtained his yeast from ginger beer. 
To render it quite pure he washed it in four times its weight of 
alcohol. ‘The yeast was not altered in its appearance; but it was 
tasteless, and was incapable of producing fermentation in a weak 
solution of sugar in water. When sugar is dissolved in water in 
such quantity as to reduce the whole to the consistence of a syrup, 
it may be mixed with yeast, and kept for any length of time wjth- 
out fermentation taking place; but the moment the mixture is 
ged diluted with water fermentation begins. 
The absorption of the gases by solid substances is a subject of 
Seiisidernble importance which had occasionally engaged the atten- 
tion of chemical philosophers. Delametherie, Morozzo, Rouppe, 
and Von Norden published successively a variety of experiments on 
2 
