C. U. C. p. ALUMNI JOURNAL 



135 



is current that "Tilghmann discovered 

 the disintegrating action of sulphurous 

 acid on wood by observing its pulping 

 effect on matches which he had used to 

 stir some of the acid contained in a 

 beaker. As told in a book entitled 

 Leading American Inventors (Henry 

 Holt & Co., New York, 1912) : "Aim- 

 lessly enough he bruised a burnt match 

 stick into a solution of sulphurous acid, 

 and next day noticed that the wood had 

 become mucilaginous, so as to look like 

 paper pulp. At once he asked : Can 

 this solution convert wood into material 

 for paper ? He put his surmise to a test, 

 and proved it to be sound." This story 

 may, however, be dismissed as having 

 no established basis in fact. 



Since the introduction of chemical 

 woodpulp is properly regarded as the 

 most important epoch in the evolution 

 of papermaking as an industry depend- 

 ent on chemistry and chemical engineer- 

 ing, and as sulphite pulp is the pre- 

 ponderating product, it may be well to 

 give some particulars of the manufac- 

 ture of this pulp. 



Sulphite pulp is the name given to 

 cellulose produced by boiling a selected 

 wood, usually spruce, in a solution of 

 calcium bisulphite or mixed calcium and 

 magnesium bisulphite, under high pres- 

 sure, until the fibers of cellulose are dis- 

 integrated and set free from the incrust- 

 ing juices, resins and gums of the tree 

 substance. 



The wood is prepared for cooking by 

 first removing the bark, and then chop- 

 ping it into pieces or chips about one- 

 fourth inch to a half inch thick. The 

 chips are afterwards crushed in a dis- 

 integrator so as to break them up into 



small pieces without, however, reduc- 

 ing them to a fineness that would result 

 in breaking the individual fibers ; for it 

 is the aim of the pulp maker to preserve 

 the cell walls of the plant unruptured 

 and undivided, as contradistinguished 

 from the aim' of the pharmacist in his 

 maceration process for the preparation 

 of a tincture or extract. 



After a screening process to remove 

 sawdust, sand and dirt, the chips are 

 elevated to a loft above large steel di- 

 gesters or boilers capable of holding 

 twenty tons of wood. The digesters are 

 filled with the chips, and cooking liquor 

 is pumped in until the container is near- 

 ly filled. The manhole or cover at the 

 top of the digester is then securely 

 fastened and steam turned on gradually. 

 xA-fter the liquor reaches the boiling 

 point the steam is kept on until the tem- 

 perature reaches 130° to 140" Cent.; the 

 duration of boiling extends from ten 

 hours to sixteen hours, cepending on the 

 temperature at which the process is car- 

 ried out and the strength of the cooking 

 liquor. 



When the period of cooking is ended 

 the accumulated gas is let off by opening 

 the gas taps at the head of the digester 

 and shutting off the steam. A tap at 

 the bottom of the digester is then opened 

 and the liquor is allowed to run out. In 

 many mills the pulp is blown out of the 

 digesters under full pressure into a large 

 vat, where it is washed and drained, but 

 in other mills the digester is filled up 

 with cold water, the pulp w'ashed once 

 or twice and finally run out into drainers 

 for subsequent treatment. 



Tilghmann, who invented the sulphite 

 process, abandoned it owing to mechan- 



