COLLECTING MARINE INVERTEBRATES. 89 



are assured cannot be damaged by a maximum of acid, put 3 

 parts of muriatic acid in 10 parts water. For thin and delicate 

 specimens, use 1 part acid to 10 of water, varying- the amount 

 of acid from 1 part to 3, as your experience will soon teach you 

 is most desirable. Put this solution in a porcelain kettle, bring 

 it to a boil, and then with a pair of wooden tongs or forceps dip 

 each shell into it and hold it there for a second or more, as may 

 be necessary. On removing it, wash it in clear water and dry it, 

 and if its appearance is not satisfactory clip it again. 



For very delicate shells, having a thin surface color, such as 

 the Cypreas and Olivias, or such shells as have very delicate 

 sculpture, the weaker solution is best. When it is desired to 

 cut more on one part of a shell than another, the acid may be 

 applied with a brush, finishing with a quick dip. Never allow 

 any of the acid solution to remain on the shell, or it will eat into 

 it and dull the lustre. For fine work, dry each specimen with a 

 towel. 



Shells which have on their exterior a great deal of horny or 

 organic matter, such as Haliotis, Ostrea, Lingula, and a few others, 

 work badly in acid, and require to be brushed constantly while 

 cutting, to remove the organic matter, for the reason .that the 

 acid acts only on the lime of the shell. 



Chloride of lime and muriatic acid are both very volatile, and 

 when not in use should be kept in tightly closed vessels. 



