OCT., igiO.] THE DECAY OF STONE ANTIQUITIES. 
103 
theories had failed, I had affected stones treated with various 
germicides, and the stones which have since best resisted the 
decay were three then treated with sulphate of copper 
(5% solution), bichloride of mercury, and creosote. 
It will be remembered that copper sheathing and copper 
nails are used to prevent the decay of the bottoms of wooden 
ships, and sulphate of copper is the preservative used in the 
manufacture of the well-known Willesden rot-proof canvas. 
It is also a very powerful germicide, and would be more 
commonly used in ophthalmia and other bacterial eye diseases 
were it not that it cause; severe smarting. Various pre¬ 
parations of copper are used by scientific agriculturists 
and foresters to destroy blights and moulds - on vegetation. 
Bichloride of mercury is much used as a germicide in surgery. 
Creosote is extensively used for preserving timber. 
I shewed Prof. Boyd Dawkins our ruins and the trial stones, 
and he said that it seemed like the localized action of some acid, 
and agreed that it was quite possible that some low organism 
might secrete acid or other material capable of disintegrating 
the stone, though this was the first suggestion of this cause 
he had heard, and finished by saying that this was, he thought, 
the most likely source of the acid. The town-soot, dirt, and 
other impurities might form a nidus in which it could develop, 
and the damp to which all outdoor stones are necessarily 
exposed, and which, in the case of the Hospitium, has never 
properly dried out since the great flood of 1892, would doubtless 
contribute. Most low organisms cannot grow if deprived 
of moisture. 
I then asked Mr. Ryan, F.I.C., the chemist to the York 
Waterworks, to do me a cultivation of a little of the dust in the 
same way as in water analysis. He did so, and he produced 
a plate cultivation with thousands of colonies. 
(Three tubes of such cultivation were exhibited, and the 
writer asked assistance from any botanists or bacteriologists 
present in identifying them.) 
The next step will be to apply some of these cultivations 
to a piece of healthy stone and see if the disease can be 
inoculated. Meanwhile, I strongly advise the application of 
sulphate of copper to a larger piece, and that means be applied 
to the Hospitium to keep it perfectly dry, such as a stove 
inside and an embankment and valve to keep out the floods 
