Xlvi PEOCEEDINGS OF THE 



The mctliod of working adopted in the slaking room having been 

 pointed out by Mr. Verini, the rationale of the process was explained 

 by Mr. John Evans, F.R.S. It was known, he said, as Clark's 

 process, by which chalk was expelled, or deposited, from water by 

 chalk. Caustic lime was mixed with water, and the lime-water 

 thus formed being injected into the water pumped up from the well, 

 which contained 16 or 17 grains to the gallon of bi-earbonate of 

 lime, caused the greater part of this to combine with it so as to form 

 a simple carbonate which being insoluble was quickly deposited at 

 the bottom of the softening tanks, leaving the water with only 

 5 grains to the gallon of the bi-carbonate of lime. 



The lime-tanks were then visited, one of which was in use 

 and had at the bottom from three to four feet of lime from the 

 slaking cauldrons. On valves being opened, soft water from the 

 reservoir, at 300 feet higher level, forces itself through a series of 

 holes in long tubes which are placed one foot apart at the bottom 

 of the tank, and by passing through the slaked lime is converted 

 into lime-water. This is then carried by a pipe into the softening 

 tanks outside, which the members next visited. 



Three of these tanks stand side by side. In the first the hard 

 water from the well and the lime-water from the lime-tank were 

 meeting, and, as JNfr. Evans had before explained, lime was being 

 deposited as a cai'bonate as the two currents — of lime-water and 

 hard water — met, forming a re-deposited chalk. After this mixing 

 process was stopped, the water, Mr. Verini said, soon cleared and 

 was ready to be pumped into the reservoir on Bushey Heath. 



In the second tank the water had become perfectly clear, and 

 was of a most beautiful blue tint, from the reflexion of white light 

 by the lime at the bottom and the absorption by refraction of the 

 more refrangible rays of the spectrum, the red rays first dis- 

 appearing, as seen in the green colour of the sea, and the yellow 

 being next refracted away, leaving only the blue. 



In the third tank the softened water had all been pumped up to 

 the reservoir, and the deposit was being washed away with water 

 from a hose, to be pumped up and stored away for sale. 



Mr. Verini then showed the height to which water could be 

 thi'own in case of fire, setting some men to send water from a hose 

 quite over the tower of the building, about 90 feet in height. 



The store room, plumbing department, and smithy, were finally 

 visited, and after a vote of thanks had been accorded to Mr. Verini, 

 the members left the water- works for the adjoining chalk-pit, 

 where, after a few fossils had been found, Mr. William Whitaker, 

 F.G.S., of the Geological Survey of England, Honorary Member of 

 the Society, gave an explanation of the section exposed. 



Mr. AVhitaker said that about fifteen years ago he gave a brief 

 description of this section.* The chalk contained flints, and de- 

 posited on it very ii'regularly was a bed of clay, the lines of bedding 



* ' The Geology of Parts of Middlesex, Hertfordshire, etc' (Memoir on sheet 7 

 of the Geological Survey Map), p. 63. 



