November 10, 1911] 



SCIENCE 



631 



been said and written by supporters of 

 the osmotic pressure and electrolytic dis- 

 sociation theories on the one hand, and by 

 those of the hydrate theory on the other, 

 should be forgotten. Far from being irre- 

 concilable, the theories are complementary, 

 and workers may, each according to his 

 proclivity, pursue a useful course in fol- 

 lowing either. One type of mind finds satis- 

 faction in using a handy tool to obtain 

 practical results; another delights only in 

 probing the ultimate nature of the material 

 with which he works. For the progress of 

 science both types are necessary — the man 

 who determines exact atomic weights as 

 well as the man who speculates upon the 

 nature of the atoms. That the want of 

 knowledge as to what the exact nature and 

 mechanism of osmotic pressure is, should 

 prevent accurate experimental work being 

 done on it, or interfere with its use in 

 theoretical reasoning, is equally ridiculous 

 with the proposition that because in the 

 theory of osmotic pressure we have a good 

 quantitative tool for the investigation of 

 solutions, therefore we should abandon 

 altogether the problem of its nature. 



The fundamental ideas of a science are 

 the gift to that science of the few great 

 masters; the many journeymen investi- 

 gators may be trusted to utilize them 

 according to their abilities. Having once 

 given his great principles to the world, 

 van't Hoff remained practically a spectator 

 of their development ; but by his single act 

 he provided generations of chemists with 

 useful and profitable fields for their labor. 

 J. Walker 



THE COAL PEODUCTION OF 

 PENNSYLVANIA 

 Pennsylvania's coal production in 1910 was 

 235,006,762 short tons, valued at $313,304,812. 

 Of this 84,485,236 short tons was anthracite, 

 valued at $160,275,302, and 150,521,526 short 

 tons was bituminous coal, valued at $153,- 



029,510. Compared with 1909, when the total 

 production of the state amounted to 219,037,- 

 150 short tons, valued at $279,266,824, the 

 production in 1910 shows an increase of 

 15,969,612 short tons, or 7 per cent., in quan- 

 tity, and of $34,037,988, or 12.2 per cent, in 

 value. Of the total increase 3,314,877 short 

 tons was in the production of anthracite and 

 12,554,735 short tons in the production of 

 bituminous coal. The value of the anthra- 

 cite production showed an increase of $11,- 

 093,713, or 7.4 per cent., and that of bitumi- 

 nous coal increased $22,944,273, or 17.64 per 

 cent. Although the quantity of bituminous 

 coal produced exceeded that of anthracite by 

 nearly 80 per cent., the value of the anthracite 

 product was larger than that of the bituminous 

 output by nearly $7,250,000. Bituminous 

 coal represented 63.6 per cent, of the total 

 output and anthracite represented 51 per 

 cent, of the total value. 



The anthracite mines of Pennsylvania gave 

 employment to 169,497 men, who worked an 

 average of 229 days. The bituminous mines 

 employed 175,403 men for an average of 238 

 days. The average production for each man 

 employed in the anthracite region was 498 

 short tons during the year. In the bituminous 

 mines the men averaged 825 tons each. The 

 daily average production for each employee in 

 the anthracite region was 2.17 short tons and 

 in the bituminous districts it was 3.61 tons. 

 According to the Pennsylvania Department 

 of Mines 601 men were killed and 1,050 were 

 injured in the anthracite mines in 1910. The 

 fatal accidents in the bituminous mines num- 

 bered 539 and the nonfatal accidents num- 

 bered 1,142. 



In the combined production of anthracite 

 and bituminous coal Pennsylvania outranks 

 any of the coal-producing countries of the 

 world except Great Britain and Germany, and 

 in 1910 it came within 10,000,000 short tons, 

 or less than 5 per cent., of equalling the out- 

 put of Germany. Pennsylvania's production 

 in 1910 was more than four times that of 

 Austria-Hungary in 1909, and more than five 

 times that of France in 1910, and nearly 20 

 per cent, of the total coal production of the 



