108 On the Composition of Organic Bodies. [Frs. 
0) Cc H 
Oxalic acid ........ Hele? SEO Ooh 
Pormictacitlaits ees eae SI ee eae 
muceiminaend Oe ee 3S+ 4+4+ 4 
Acehe aden: SMAPS ois? 83+ 4+ 6 
Pe rei Ce Ts nee eee a 34+ 6+ 6 
Bengoreacid™. ye eo0 se os 3+ 15 + 12 
You will excuse me for not having adopted your correction of 
my analysis of oxalic acid. Let it be shown by experiment that 
oxalic acid gives more water when decomposed than I found, and 
I will give up the point immediately. You have no doubt observed 
that other chemists have gone to the other extremity, that of deny- 
ing the existence of hydrogen altogether in oxalic acid, and of 
considering it as carlonous acid. But that idea does not appear 
probable to me. Iam, &c. 
JacoB BERZELIUS. 
ArTICLE IV. 
To find the Heights of Mountains with the Barometer, by Means 
of a Table of Compound Interest. By Adam Anderson, Esq. 
Kector of the Perth Academy. 
(To Dr. Thomson.) 
DEAR SIR, 
The usual method of finding the altitudes of mountains with the 
barometer, by means of a table of logarithms, being founded on the 
principle that the density of the air decreases in a geometrical 
ratio, while the corresponding heights increase in an arithmetical 
progression, or, in other words, that the heights are the logarithms 
of the densities, it occurred to me that a table of compound in- 
terest might be conveniently substituted for a table of logarithms 
when the latter could not be procured; more especially as all the 
amounts necessary may be obtained in a few minutes by the actual 
involution of the amount of 1/. for a year. 
A table of the amount of 1/. compound interest is obviously a 
system of logarithms the base of which is the amount of 1/. for a 
year, and the successive years a series of logarithms the numbers 
corresponding to which are the opposite amounts. Hence the ex- 
pression for the difference of altitude between two stations may 
easily be reduced from Brigg’s logarithms to what may be called im- 
terest logarithms, by help of the well-known property that in diffe- 
rent systems the logarithms of the same number are inversely as the 
logarithms of the bases of the systems, the latter being taken ac- 
cording to any system whatever. 
