24 Mr. Davy s Lecture on the Decomposition and Composition 
With respect to the fixed and volatile oils and naphtha in 
their different states, there is a perfect coincidence between 
the effects of the two new substances, except in the difference of 
the appearances of the saponaceous compounds formed : those 
produced by the oxydation and combination of the basis of 
soda being of a darker colour, and apparently less soluble. 
The basis of soda, in its degrees of oxydation, has precisely 
similar habits with the basis of potash. 
When it is fused with dry soda, in certain quantities, there 
is a division of oxygene between the alkali and the base ; and 
a deep brown fluid is produced, which becomes a dark grey 
solid on cooling, and which attracts oxygene from the air, or 
which decomposes water, and becomes soda. 
The same body is often formed in the analytical processes 
of decomposition, and it is generated when the basis of soda 
is fused in tubes of the purest plate glass. 
There is scarcely any difference in the visible phenomena 
of the agencies of the basis of soda, and that of potash on 
sulphur, phosphorus, and the metals. 
It combines with sulphur in close vessels filled with the 
vapour of naphtha with great vividness, with light, heat, and 
often with explosion from the vaporization of a portion of 
sulphur, and the disengagement of sulphuretted hydrogene 
gas. The sulphuretted basis of soda is of a deep grey colour. 
The phosphuret has the appearance of lead, and forms 
phosphate of soda by exposure to air, or by combustion. 
The basis of soda in the quantity of renders mercury 
a fixed solid of the colour of silver, and the combination is 
attended with a considerable degree of heat. 
It makes an alloy with tin, without changing its colour, and 
