BYNE : THE CORROSION OF SHELLS IN CABINETS. 173 



I have added an Appendix, which contains purely chemical matter, 

 being a detailed account of the experiments performed, which can 

 if necessary be repeated by other workers. It has been a matter of 

 regret that, with the exception of a short note by Mrs. Kenyon, 1 there 

 is no literature to consult ; and, consequently, it was doubtful what 

 course my investigation should take. 



The shells which formed the subject of my experiments were from 

 the National Collection at South Kensington, furnished me through 

 the courtesy and kindness of Mr. E. A. Smith. These alone are 

 referred to unless where otherwise distinctly stated. The shells in the 

 cabinet drawers are in many instances either partially or entirely 

 destroyed, the surface being corroded and covered with a fine white 

 powdery substance, which can easily be scraped off with a knife. 

 This causes them to resemble Eocene mollusca. 



Many species are quite unrecognisable on account of the surface 

 being eaten away so deeply. The destruction has travelled from shell 

 to shell and drawer to drawer, like a disease, several valuable speci- 

 mens having been spoilt. The mischief has assumed large propor- 

 tions, and being still on the increase, causes the greatest anxiety. 

 The most remarkable facts are : — 

 1. — Only marine species are attacked. 

 2. — H'ghly-polished shells, such as those of Cypnea, are the most 



liable to be affected. 

 4. — It does not extend to every specimen in a drawer, and of 

 several mounted on the same tablet, perhaps one only is 

 attacked. 

 4. — Loose shells are also destroyed, but there are comparatively 

 few of these compared with the number of those mounted on 

 cards. 

 5. — The shells affected are from twenty to fifty years old, but the 

 corrosion does not appear until after the lapse of about ten 

 years. The process is thus an extremely slow one. 

 6. — It occurs principally amongst the shells kept in drawers in 



the dark, where the air is confined and seldom changed. 

 7. — If the tongue be placed against one of the shells, an astrin- 

 gent alum-like taste will be observed. 

 We now come to the consideration of possible causes of the corro- 

 sion. They appear to me to be four in number. 



I. — Damp. 

 If the shells were placed in a room or gallery that was not properly 

 warmed, a very probable reason would be that a fungus had been 



1 Notes on the Effects of the Atmosphere on the Shells of Mollusca, Proc. Roy. Soc, 



Tasmania for 1896, p. 88, 1897. 



