The accompanying table shows the figures obtained from three large blocks from the Meten Chamber. They represent the number of cubic centimetres of decinormal silver solution used for 100 c.c. of the water, which was changed every fortnight. The first column on the left shows the dates upon which the stones were placed in the tubs:
+-------+-------+-------+-------+-------+-------+-------+-------+-------+ |3 Feb. | 7 Apr.| 4 May | 2 June|25 Aug.|22 Sep.| 4 Nov.| 1 Dec.|12 Jan.| | 1890 | | | | | | | | 1891 | +-------+-------+-------+-------+-------+-------+-------+-------+-------+ | | 3·0 | 2·5 | 2·3 | 1·4 | 1·0 | 0·9 | 0·8 | 0·8 | +-------+-------+-------+-------+-------+-------+-------+-------+-------+ |25 Apr.| 9 May |18 July| 1 Aug.|25 Nov.|23 Dec.|16 Feb.|29 Aug.|12 Sep.| | 1893 | | | | | | 1894 | | | +-------+-------+-------+-------+-------+-------+-------+-------+-------+ | | 6·0 | 5·6 | 4·9 | 2·0 | 1·7 | 1·5 | 0·8 | 0·8 | +-------+-------+-------+-------+-------+-------+-------+-------+-------+ |29 July|28 Oct.|25 Nov.|23 Dec.|20 Jan.|16 Feb.| 1 Aug.|29 Aug.|12 Sep.| | 1893 | | | | 1894 | | | | | +-------+-------+-------+-------+-------+-------+-------+-------+-------+ | | 3·0 | 2·0 | 1·5 | 1·3 | 1·1 | 0·7 | 0·8 | 0·7 | +-------+-------+-------+-------+-------+-------+-------+-------+-------+
When repeated examinations gave a fairly constant result of 0·7-0·8 cubic centimetre the process was regarded as complete, for Berlin tap-water itself contains small quantities of chlorine compounds, 100 c.c. requiring from 0·4 to 0·6 c.c. decinormal silver solution. Before using the water from a well or from waterworks, it should be examined to ascertain the number of cubic centimetres of silver solution required to produce the red colouration. As the amount of chlorine compounds in the water may vary it is advisable to repeat the examination[89].
The following table shows the rapidity with which salts can be completely extracted from small pieces of limestone. The limestones were placed in tap-water in three glass cylinders, each containing 2 litres; the amount of silver solution required for the water was 0·45 c.c. per 100 c.c.
+-----------------------+--------+---+---+---+---+---+------------------+ |No. of days of soaking | | | | | | | | | in water | 1 | 1 | 1 | 2 | 2 | 4 | | +-----------------------+--------+---+---+---+---+---+------------------+ |1|Weight in grammes 107|3·4 c.c.|1·4|1·1|0·7|0·5|0·5|cubic centimetres | | | | | | | | | | of decinormal | | | | | | | | | | silver solution.| | | | | | | | | | | |2|Weight in grammes 66|3·0 c.c.|1·2|0·7|0·5| --|0·5|cubic centimetres | | | | | | | | | | of decinormal | | | | | | | | | | silver solution.| | | | | | | | | | | |3|Weight in grammes 47|3·6 c.c.|0·8|0·6|0·5| --|0·5|cubic centimetres | | | | | | | | | | of decinormal | | | | | | | | | | silver solution.| +-+---------------------+--------+---+---+---+---+---+------------------+