THE MUSEUMS JOURNAL. 
[VOL. IO. 
IO4 
which happen every few years, and one of which has not 
recently occurred.* 
DISCUSSION. 
Mr. H. Bolton said that in the Bristol district the Bath 
stone which was much used as a building stone, had to be carefully 
handled as it bruised readily, and in that way offered facilities 
for weathering agents to operate. 
Mr. T. Sheppard laid stress upon the action of carbonic acid 
in destroying stone. By far the greater amount of erosion which 
went on in the district from which he came was due to the influence 
of the weather. 
Mr. H. M. Platnauer said that in considering the respective 
actions of carbon and sand they must take into consideration 
the fact that one was oxydized and the other was not. He 
must deprecate any comparison between the action of organisms 
on wood and stone, for the very simple reason that one was 
purely organic and the other was not. 
Mr. E. E. Lowe mentioned the conditions existing at Croft, 
near Leicester, where the syenite is decomposed to a depth of more 
than eight feet, and thought that the agent; producing such an 
extensive decomposition should be taken into consideration. 
Mr. E. M. Holmes remarked that the disintegration of the 
stone might be due to the action of carbonic acid in dissolving 
the carbonate of lime in the presence of rain, and leaving the 
carbonate of magnesia in the stone in a crumbling state. This 
action could be seen at Roker, near Sunderland, on the magnesian 
limestone rock. Some lichens secreted oxalic acid ; others, 
especially of the genera Verrucaria and Lecidea , eroded limestone 
rocks, and it was quite possible that the early stages of such lichens 
might be present in the stone, as the spores of lichens were con¬ 
stantly present in the air, and the algal portions of lichens were 
killed by a solution of sulphate of copper, which might account 
in part, at all events, for the results obtained by Dr. Anderson. 
It would not be possible to determine the nature of the cultures 
* [Author’s Note.—Since the above was in type I have seen Dr. Delepine, 
Professor of Comparative Pathology and Bacteriology in the University of 
Manchester. He tells me that he constantly has diseased stone submitted to 
him for examination, and frequently finds the cause to be various 
micro-organisms, which do not all require the same treatment. He showed 
me at the Public Health Laboratory, of which he is Director, a bundle of 
such specimens just received from the City Architect, and also cultivations 
from others in various stages. He mentioned sulphate of copper as one of 
the most useful applications.] 
