916 REPORT OF COMMISSIONER OF FISH AND FISHERIKS. 



a cistern " rests upon a second cistern." The upper one (of wood or 

 otlicr material) is lined with metal in such manner that a non-conduct- 

 ing substance maybe inserted into the spaces " which are left at certain 

 parts between the sides of the cistern and the lining, and between its 

 iioor and lining." A yAnte " extending along two sides of the cistern" 

 divides oft' a chamber (called the salt-chamber), and another idate on 

 the opposite sides divides off a smaller chamber (called the water-cham- 

 ber) which communicates with a central chamber by a pipe on the under 

 side of both. The central chamber contains "a series of guides or tubes 

 arranged alternately close on to and a little above" the bottom lining, so 

 as to cause "an upward and downward current of the cooling solution." 

 "An insulating partition on all the four sides" (comiiosed of x>lates with 

 charcoal powder between them) divides off a chamber " from the space 

 or chamber immediately around the central chamber." And this sj^ace 

 is occui)ied by the vessels which contain the water to be frozen. The 

 lower cistern contains a coil of i>ipes, and the overiiow from the ujjper 

 cistern is indicated by an outlet pipe into the lower one, and surrounds 

 the coil. A pump raises the solution, as may be required, from the lower 

 cistern to a third cistern, which is mounted over a boiler, and communi- 

 cates vv ith it by a i)ipe carrying a ball tap. A pipe passing from the boiler 

 is extended into a worm inside the third cistern ; it then descends and is 

 unil^ed with one end of the coil in the lower cistern; the other end of the 

 coil extends upwards " and bends over and into the water-chamber." 

 There is a discharge-tap from the boOer, and under the tap is " a crys- 

 tallizing vat." The central chamber is filled with crystallized chloride 

 of calcium. The vessels are filled with the substance to be frozen, and 

 are closed with insulating covers. The water-chamber is filled yvith. 

 water, which passes into the central chamber, and penetrates " a con- 

 siderable mass of the crystals in passing upwards and downwards be- 

 tvv'een the tubes or guides into the space or chamber around." The 

 solution fills this space " up to the level of the overflow of the insulating 

 partition," and passing between tlie vessels "descends into the narrow 

 surrounding chamber" ; when this is filled, the surplus is discharged by 

 the outlet-pipe into the lower cistern. Here the solution absorbs a fur- 

 ther x^ortiou of heat from the coil "containing condensed water from the 

 boiler." The pump raises the solution into the third cistern ; the solu- 

 tion descends, iind, having "reached its proper level in the boiler," is 

 made to boil. The steam passing through the pipe and worm is con- 

 densed by contact with the solution in the third cistern; it then descends 

 into the coil in the lower cistern, "is considerably cooled by contact 

 with the solution" in this cistern, and rises thence into the water-cham- 

 ber, "to be there almost reduced to the freezing-point pre\aous to its 

 again entering " the central chamber. " The concentrated solution is 

 drawn from the boiler from time to time," is received into the crystal- 

 lizing vat, and is there crystallized in from 12 to 24 hours. The crystals 

 thus obtained are put into the salt-chamber "to be cooled down to nearly 



