No. 58. — 1907.] ROMAN COINS. 



189 



Appendix. 



Every coin collector knows what endless toil and trouble, 

 besides straining of the eyes, is incurred in the cleaning of old 

 coins that are caked with green or red patina. A certain 

 amount of this incrustation can be loosened by the use of lime 

 juice, citric acid, &c, but in a large number of cases the only 

 method which seems available is the use of a knife. This is 

 not only a great trouble and a danger to the coin, but often 

 the result is unsatisfactory. 



It may therefore be of interest to briefly describe the 

 method adopted by the Archaeological Survey Department. 

 The method is the invention of Herr Krefting, and is described 

 in detail in a little book called " The Preservation of Anti- 

 quities," published by the Cambridge University Press. The 

 results are most satisfactory. If the inscription or design that 

 was on a coin is completely gone, this method of treatment 

 can do nothing. But if the inscription is still there and only 

 obscured by a hard crust of patina, Kref ting's method will 

 bring it out in the most wonderful manner, at the same time 

 rendering all the incrustations so soft and soluble that they 

 can easily be removed by rubbing the coin between the fingers 

 with brickdust and water. 



The modus operandi is as follows : A thin sheet of zinc must 

 be perforated with a bradawl of about \ inch diameter at 

 intervals of about 2 inches round the sides and at similar dis- 

 tances across the centre. This is placed flat with the sharp 

 edges of the holes uppermost, and on it are laid the copper 

 coins, each distant from its neighbour about the length of its 

 own diameter, that is to say, on a sheet 6 in. by 6 in. about 

 sixteen coins, each f inch in diameter, can be laid, and there 

 will be a similar number of holes. On this is superimposed an 

 exactly similar plate of zinc and another layer of coins. In 

 this way six or eight double layers — -zinc and coins — can be 

 laid, so that each sheet rests on the edges of the holes in the 

 sheet below, and on the top is placed a covering sheet with the 



