Salt does very little to preserve butter. It retards the decomposition
of the caseous and albuminous materials left in it; but if butter is
properly made of cream not mixed with loppered milk and is completely
washed with pure water, it is a fair question if butter will not keep
longer without salt than with it. There are instances on record where
butter has been kept sweet without salt for a long time. We half
suspect that, though salt at first retards decomposition, the salt
itself, in time, decomposes and becomes sodium and chlorine gas, or
enters into new combinations with the constituents of the butter, and
thus makes new compounds that do not in the least improve the flavor.
We have no positive evidence of this, but have had this suspicion
awakened by facts related about the keeping of butter and by a process
of general reasoning. It is true that salt is one of the most stable
compounds known, but we have proof that it can be resolved into its
original elements, when stronger affinities are presented for one or
both of them to unite with. It would not, therefore, be strange if such
decomposition sometimes follows when used in our food preparations.