On the Topography and Soil of Paris. 293 
We may therefore establish the following principle, 
which expresses in a general manner what I have detailed 
in this memoir. 
When the vegetable acids are pure, there are none of 
them, if we except the acetic acid, which can, by combi- 
ning in anymanner with alcohol, lose their acid properties ; 
but when they contain a mineral acid capable of strongly 
condensing the alcohol, all these acids form, on the con- 
trary, with this body, a combination of such a nature that 
their acid properties disappear, and yet without the mineral 
acid making part of the combination. 
This principle being recognised, there is no reason why 
it ought not to include the animal acids. Probably it will 
extend to the mineral acids, and we shall thereby discover 
the means of combining them easily with alcohol ; and 
even perhaps we shall be permitted to combine all the ve- 
getable and animal substances, if not with all the acids, 
at least with those which are, strong and concentrated. 
What is at least certain is, that it may become fertile in re- 
sults, since it increases our means of combining matter. 
However the case may be, I shall proceed with my in- 
quiries. T shall inquire whether the mild vil of wine is not 
formed of alcohol and sulphurous acid; and if the kind of 
oil which we obtain on passing exymuriatic acid through 
alcohol is not itself composed of alcohol and muriatic acid. 
I shall examine the properties of the various combinations 
which I have made known. I shall try to decompose them 
by different salts, and thus to combine, by means of double 
decompositions, alcohol with all the mineral acids. 1 shall 
above all endeavour to ascertain if there exists a perfect 
identity between those kinds of combinations the forma- 
tion of which is indirect, and the nitric and muriatic ethers 
the formation of which is direct. Finally, I shall try to 
determine if really (condensation excepted) the mode of 
combination is the same when a vegetable acid is dissolved 
in alcohol without losing its acid properties, and when 
on the contrary, by being intimately combined with this 
‘body, its acid properties disappear. 
AXXIX. Extract from a Memoir on the Topography Wott 
the upper Strata (le Relief) of the Soil of Paris. By 
P. S. Grrarp *, 
HE plains on which the city of Paris is situated were 
formerly covered by the waters of the Seine, whenever that 
* Nouveau Bulletin des Sciences, par la Sdcicté Philomathique. Paris, 1808. 
river 
