36o 



THE PREVENTION OF CORROSION IN SHELLS. 



By L. St. G. BYNE, M.Sc. 



(Read before the Society, February, 14th, igo6). 



Since the publication of my two former papers upon the important 

 matter of the Corrosion of Shells in Cabinets, I have had a few 

 instances of this mischief brought to my notice. In all these the 

 symptoms have been the same, and very characteristic, namely, the 

 white powdery efflorescence and the vinegar-like aromatic odour. 

 This latter is a most fortunate thing, for it enables specimens which 

 have become affected to be at once dealt with. The only affected 

 shell in my own collection so far has been a Cyprcea argus, which I 

 at once burnt. One correspondent cracked up his spoilt shells and 

 gave them to his fowls to peck at. 



There is a spurious form of trouble which is that of bleaching by 

 the sun on tropical shores. I had an example of C. argus from 

 North Borneo bleached snow-white all over the dorsal surface. 



Nothing has since transpired to make me alter my opinion that the 

 mischief is the result of the action of Bacilli. I have been led to 

 this by extensive chemical experiments, which show that the white 

 efflorescence is mainly composed of calcium butyrate, produced by 

 the action of butyric acid on the calcium carbonate of the shell 

 structure. This butyric acid must be the result of the presence of 

 the bacillus of butyric fermentation. I fail to see what other 

 explanation there can be. Pieces of animal left in the shells may 

 be responsible. I have dealt with this fully in my second paper. 



I willingly admit that I have never isolated any definite bacillus, 

 as I have neither the knowledge nor means of doing so. It should 

 be possible for a bacteriologist to obtain a culture by placing 

 sterilized glycerine in a glass bell jar containing corroded shells. 



I have not seriously considered the action of damp, because it has 

 not come into any case that I have looked into. In the National 

 Collections, South Kensington, where corrosion is rife, the rooms, 

 etc., are very dry. Nor does the suggestion of Mrs. Kenyon that 

 " saline particles " are responsible recommend itself to me. 



The method of prevention I now recommend is of the simplest 

 nature. The shells must first be thoroughly soaked in water, rubbed 

 with soap, and then perfectly dried. They are then to be rubbed 

 over with a small quantity of linseed oil, any excess being removed 

 with a rag. I am quite sure that this treatment will act efficaciously. 

 I formerly recommended soaking the shells in a solution of corrosive 



