3 * 
of the fixed Alkalies. 
r 
The experiments which have been just detailed, are those 
in which the largest quantities of materials were employed ; 
I have compared their results, however, with the results of 
several others, in which the decomposition of water was 
performed with great care, but in which the proportion of 
the bases was still more minute: the largest quantity of oxy- 
gene indicated by these experiments was, for potash 17, and 
for soda 26 parts in 100, and the smallest 13, and 19 ; and 
comparing all the estimations, it will probably be a good 
approximation to the truth, to consider potash as composed 
of about 6 parts basis and 1 of oxygene ; and soda, as consist- 
ing of 7 basis and 2 oxygene. 
VII. Some general Observations on the Relations of the Bases of 
Potash and Soda to other Bodies. 
Should the bases of potash and soda be called metals ? The 
greater number of philosophical persons to whom this question 
has been put, have answered in the affirmative. They agree 
with metals in opacity, lustre, malleability, conducting powers 
as to heat and electricity, and in their qualities of chemical 
combination. 
Their low specific gravity does not appear a sufficient 
reason for making them a new class ; for amongst the metals 
themselves there are remarkable differences in this respect, 
platina being nearly four times as heavy as tellurium ;* and in 
* Tellurium is not much more than six times as heavy as the basis of soda. There 
is great reason to believe that bodies of a similar chemical nature to the bases of 
potash and soda will be found of intermediate specific gravities between them and 
the lightest of the common metals. Of this subject, I shall treat again in the text in 
some of the following pages. , 
