Mat 25, 1917] 



SCIENCE 



491 



would have been absolutely helpless. The 

 first of these is the health of the laborers. 

 The French undertook to build the canal 

 years ago, and while their failure was 

 brought about by several causes perhaps 

 one of the most important was the fact that 

 the men could not live in that part of the 

 world and retain their health. Yellow 

 fever and malaria were everywhere, and it 

 was but a matter of time when one must be 

 attacked by one or both of these infections. 

 It has been stated that the building of the 

 railroad across the Isthmus meant the death 

 of a man for every tie that was laid. But 

 man can live in Panama now with perfect 

 safety, so far as yellow fever is concerned, 

 and this is due entirely to discoveries with 

 which Col. Goethals had nothing to do. 

 Dr. Gorgas was in immediate charge of the 

 work of sanitation, but it was kerosene, the 

 product of the chemist, which was sprayed 

 on the stagnant pools, and which checked 

 the development of the mosquito. 



In the second place, the penetration of 

 Gulebra, as well as the remainder of the 

 blasting necessary, woi^ld have been impos- 

 sible without the powerful explosives of the 

 chemist. The gun-powder, dynamite, blast- 

 ing gelatin and similar substances are all 

 products of the chemical laboratory. 



In the third place, let us suppose that 

 the development of the mosquitoes has been 

 checked, that Culebra has been pierced — 

 the work is only half done. It is necessary 

 to control the level of water in the canal, 

 and this, under the conditions imposed, can 

 be done in only one way, namely, by the 

 construction of locks and dams. For these 

 some material stronger than wood and less 

 easily corroded and destroyed than iron 

 must be used, and this is found in the chem- 

 ist 's cement. As is well known, thousands 

 of barrels of this material were used in the 

 work. 



Finally, when the canal is complete and 



ships are passing back and forth through 

 it, there is comparatively little safety until 

 it has been fortified. The chemist's powder 

 and steel must stand guard over it as they 

 do over every treasure we own, or we should 

 not be able to retain it as a national posses- 

 sion. 



Cases of this kind could be multiplied 

 indefinitely, but I must not take your time 

 to do so. On the other hand, the Panama 

 Canal is so remote that many persons do 

 not think of it as having any bearing what- 

 ever on their daily lives. But the question 

 of food and war munitions at this time can 

 hardly be misunderstood by any, and it re- 

 mains merely to show the relations of chem- 

 istry to these to convince the most indiffer- 

 ent. A detailed discussion of even these 

 would tax your patience, I fear, therefore I 

 shall limit myself to the consideration of a 

 single element, viz., nitrogen. 



It has long since been proved that nitro- 

 gen is an essential constituent of the food 

 of all living beings, and that, in general, it 

 may not be assimilated if taken directly 

 from the air where it is present in the free 

 form. It must be combined with one or 

 more other elements. As one begins the 

 study of nitrogen in a chemical laboratory, 

 he finds what at first sight appears to be a 

 relatively uninteresting element. It has 

 neither color, odor nor taste, is but slightly 

 soluble in water, and does not readily com- 

 bine directly with other elements. But in 

 combination it is a constituent of many dif- 

 ferent substances of the most varied char- 

 acters. It is present in some of the most 

 delicate of perfumes as well in substances 

 whose odors suggest utter vileness. It is a 

 constituent of various fibers (wool, silk, 

 artificial silk) used in our clothing, and 

 also of the aniline dyes which enhance their 

 beauty and value. It is present in the most 

 potent of medicines and in the most deadly 

 poisons. As gunpowder it drives our bul- 



