616 EXPERIMENT STATION RECORD. 



the time of cooking, tlie lower the yields of pulp, and the lighter and easier to 

 bleach. Caustic soda had twice the reducing power possessed by sodium 

 sulphid." 



The 19 semicommercial cooks made gave a yield of pulp corresponding to 49 

 per cent of the dry weight of the wood. The paper made from the pulp was 

 stronger and tougher than the kind usually imported known as " kraft paper." 

 The paper made from the soda pulps of the same wood were not so strong and 

 the yield was less. 



[Report of the] division of oils and varnishes, R. W. Darner (North 

 Dakota 8ta. Rpt. 1912, pt. S, pp. 484-490). — This report presents analyses of 

 linseed oils and turpentines and data as to Chinese wood oil and lumbang oil. 



Some of the linseed oils were found adulterated with mineral oil. The turpen- 

 tine oils examined all seemed uniformly adulterated with from 15 to 20 per 

 cent of a light mineral oil. Analyses of two pure samples of Chinese wood oil 

 are reported and the chemical and physical data compared with commercial 

 samples. They agreed well so far as specific graA'ity, refractive index, saponifi- 

 cation number, and unsaponifiable matter were concerned but disagreed in the 

 iodin number which ran higher in the commercial samples. 



"The Bacon heat test was applied [to the pure samples] and a good solid 

 'go back' was obtained in each case. Where the test was applied to the com- 

 mercial samples only one was found that responded to the test, and that gave 

 a rather pasty solid. On inquiring into the history of these oils as to their 

 usefulness in varnish and paint making, it was found that each sample filled 

 the requirements. This would tend to show that while Bacon's test will indi- 

 cate purity of some samples, yet it does not indicate the usefulness of the 

 sample in paint and varnish manufacturing." 



A heat test was also used, with which each of the samples responded with 

 good " go backs." In this, 20 minutes was taken to bring 100 gm. of oil to 

 225° C, at which temperature it was held for 20 minutes; 10 minutes was then 

 taken to raise the oil to between 270 and 280° where it was held for 8i minutes. 



This method has the advantage over Bacon's method in that the oil is held 

 for 20 minutes at the same temperature used in varnish making. It also de- 

 termines whether the oil darkens or changes in viscosity, which is of the 

 utmost importance to the varnish maker. 



The data with reference to lumbang oil has been previously reported (E. S. 

 R., 29, p. 811) with the exception of an additional sample of oil obtained from 

 other sources. This differed from those previously reported in the high saponifi- 

 cation number and specific gravity. 



Oxygen absorption of linseed oil, R. W. Daeneb (North Dakota 8ta. Spec. 

 Bill, 3 (1914), ^0. 1, pp. 8-11, fig. 1). — It is pointed out that in only one of the 

 experiments cited in the literature quoted was the light factor considered, and 

 in none was the effect of moisture, which has been proved to have a great 

 effect upon the drying of oil and paint films, noted. " This work was under- 

 taken to see if under conditions that would be easily controlled all pure lin- 

 seed oils would dry in about the same time. The drying tests were made in a 

 glass case 12 in. high, 12 in. wide, and 24 in. long. This case sat on a base 

 containing a mercury seal, so that the case was air-tight and at the same time 

 could easily be lifted and the drying plates taken out and weighed. 



" The air was first dried before being drawn through the case by a train of 

 sulphuric acid and calcium chlorid tubes and then warmed to 25° G. by being 

 drawn through a glass spiral tube surrounded with warm water. The humidity 

 within the box was kept constant by exposing a No. 2 beaker containing water. 

 The temperature within the box never varied more than 0.5° from 25°. Light 

 was supplied by two 240 watt tungsten lamps provided with reflectors. The 



