The same difficulty which arose in the treatment of the Meten limestones was frequently met with in the treatment of these ostraca. Those which were of a dark brown colour especially, and to a less degree also the red and the yellow, were covered with a slimy growth of algae. As the script is easily destroyed no attempt should be made to remove these algae from the side which bears the script even with the softest brush, although they should from time to time during steeping be brushed from the underside. The inconvenience caused by algae is, however, less marked in the treatment of earthenware, the light and porous character of which renders prolonged steeping needless, nor is there the same necessity to continue the steeping for the purpose of chlorine estimation. The following results were obtained in the treatment of 13 fragments, the average thickness of which was 1 cm. [3/8th inch], with an average superficial area of 1/10 sq. metre [4 inches]. The tub in which they were steeped contained 85 litres [18-1/2 gallons] of water.
100 cubic centimetres of the tap-water used were found to require 0·5 c.c. of the silver solution, and on each occasion this quantity of the water was tested.
+------------+-----+-----+-----+-----+-----+-----+-----+-----+----------+ | Water | | | | | | | | | | changed | | | | | | | | | | | after | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 4 | 5 days | +------------+-----+-----+-----+-----+-----+-----+-----+-----+----------+ | 100 c.c. of| | | | | | | | | | | the water | | | | | | | | | | | used in | 3·0 | 1·3 | 1·0 | 0·8 | 0·9 | 0·7 | 0·7 | 0·6 | 0·6 c.c. | | steeping | | | | | | | | |of silver | | required | | | | | | | | | solution | +------------+-----+-----+-----+-----+-----+-----+-----+-----+----------+
The water was changed at first daily, then every two days, and so on: the steeping could therefore be regarded as complete at the end of a fortnight.
A small figure of earthenware, which weighed only 28·9 grammes, was steeped in 1-1/2 litres of distilled water, and gave the following result for every 100 c.c. used:
Water changed after 2 days required 3·6 c.c. silver solution.
Water changed after 3 days required 0·4 c.c. silver solution.
Water changed after 4 days required 0·0 c.c. silver solution.