NEW BRUNSWICK FORESTRY CONVENTION 



which it stands, it forms a most imposing landmark which may be seen from 

 a long distance on the surrounding plain. Primarily the structure consists 

 of a series of great wooden pipes bound together and braced by iron bands 

 .and rods to withstand wind pressure. The wooden pipes are filled with 

 lime stone, and the entire arrangement is such as to present the greatest 

 surface contact between the gas and water on the one hand, and on the other 

 hand between the disolved acid and the limestone, with which the pipes are 

 ^tilled. A series of pipes provide for the admission of the sulphur fumes into 

 the wooden pipes both at the top and bottom, while water pipes provide for 

 :the introduction of water at the top. 



SULPHUR RETORTS 



In a small room at the base of the tower is a double series of retorts 

 where the sulphur is burned. The sulphur is of a very fine grade and is ob- 

 tained from Sicily. It is placed in large hoppers, whence it is slowly fed 

 into the retorts at the base. As the fumes are generated, they ascend 

 through metal pipes and find their way into the Hme both at the top and 

 bottom of the stack. As the water introduced above descends it dissolves 

 ihe gaseous acid in large quantities, often to the extent of ten per cent. As 

 this solution in turn passes down over the surface of the limestone, it is ab- 

 sorbed by and combines with the latter with the formation of a soluble bi- 

 sulphite of lime which in turn passes into solution in the descending water, 

 -and it is thus eventually brought down to a large storage tank, where it is 

 accumulated for future use. From this tank it is introduced into the digester, 

 which has been charged with the chips already described. When the wood 

 and the acid have thus been brought together, steam is introduced from be- 

 low and the pressure is raised to 70 pounds. The digestion is carried on 

 dor several hours until, as determined by the experience of the operator and 

 ithe indications of the liquor, certain changes have been effected. The nature 

 of these changes is of great interest from a chemical point of view, but they 

 .hardly lie within the scope of our present discussion. Upon their com- 

 pletion, however, the bottom valves are opened, the steam pressure is re- 

 versed, and the' contents are driven off into the blow off" tank, after which 

 .a fresh charge is introduced and the process is repeated. In this way each 

 digester receives two " cooks " each day, and 60 tons of chips become con- 

 verted into pulp. The " blow oft " tanks are immense wooden constructions 

 about thirty feet deep, and of corresponding diameter. They are provided 

 with sieve-like bottoms, through which the washed pulp is forced into tubes, 

 which in turn convey it to the scraen room. There it is passed over screens 



