DISCOVERY 



273 



in so far that it was raised from the disrepute into which 

 it had fallen, through the charlatanism of its followers, 

 to the status of a subser\-ient branch of medicine. 



The basis of iatrochemistry was the application to 

 the human body of the statement that all substances 

 consist of one or more of three constituents. Paracelsus, 

 for instance, considered that all disease was caused by 

 a preponderance of one constituent. Health could be 

 restored by removal of this excess by suitable medicines. 

 This theory was responsible for a large number of 

 experiments to determine the physiological action of 

 different substances, usually metallic derivatives and 

 alkalies. The word alkali was first used by Van 

 Helmont (1577-1644) in its present sense. Sylvius 

 suggested that the corrosiveness and sharpness of 

 alkalies were due to the fire-stuff taken up during their 

 preparation, this being usually effected by calcination 

 or by boiling with lime. Tachcnius first defined a salt 

 as the compound of an acid and an alkali. The iatro- 

 chemists were concerned more with the application of 

 chemistry to the workings of medicine than with 

 advance in the science of chemistry. We find, there- 

 fore, that any such advance which took place in this 

 period was rather in the recognition of new substances, 

 and an examination of their action upon the human 

 body. 



The next distinct period in the history of chemistry 

 dates from the beginning of the eighteenth century, 

 when Stahl (1660-1734) formulated his famous theory 

 of phlogiston. He considered that the property of 

 combustibility is dependent upon a constituent of 

 all combustible bodies, to which he gave the 

 name phlogiston (from <^Aoyio-T£u), set on fire). This 

 constituent could pass from one body to another ; 

 addition of phlogiston to some substances could, for 

 example, be obtained by the action of what we should 

 now call a reducing flame upon them, or by heating one 

 body with another which readily parted with its phlo- 

 giston. Accordingly, he believed metals to be com- 

 pounds of metallic oxides with this hypothetical 

 phlogiston. A difficulty arose when it was found that 

 a body was lighter after the addition of phlogiston 

 than before. This was met by the more ardent 

 supporters of the theory by saying that the laws of 

 gravitation were reversed in the case of phlogiston ; in 

 fact, its weight was a negative quantity. 



The period of phlogiston contained many great 

 chemists, of whom, possibly, Boyle, Scheele, Cavendish, 

 and Black were the most prominent. Boyle is famous 

 for his work upon gases and the well-known law de- 

 duced therefrom. He was, also, the first chemist to 

 define an element as a substance which can enter into 

 combination, but which itself carmot be decomposed. 

 Scheele discovered chlorine and investigated its pro- 

 perties. To Priestley is the credit of many experiments 



upon gases, in the course of which he discovered oxygen. 

 The work of Black upon the alkaline earths was 

 important since it showed where the difference lay 

 between caustic and mild alkalies. He proved that 

 the former were alkali oxides, and the latter, carbonates. 

 Black also investigated the properties of carbon dioxide 

 given off during these experiments. In view of these 

 advances it is strange to find that, until Lavoisier 

 definitely disproved it, the belief in the conversion of 

 earth into water and similar processes still flourished. 

 In this, and in Stahl's theory of phlogiston, we are 

 reminded of the older theory of four distinct principles 

 or elements in matter, which we find occurring in every 

 part of the world and which seems to have existed from 

 time immemorial. 



In spite of the almost universal acceptance of Stahl's 

 erroneous theory, the science of chemistry greatly 

 increased during the period of the phlogistonists. For 

 the first time chemistry was established as a real and 

 independent science. The foundation-stone was laid 

 upon which the structure of chemistry as it is known 

 to-day is built, that structure which the genius of 

 Lavoisier did so much to rear and which, as we regard 

 it, should remind us of the labours of those who worked 

 with such endurance and with so little visible reward. 



The Psychological Exami- 

 nations in the American 

 Army 



By Walter Veazie, Ph.D. 



Instructor in Philosophy, S'civ York Universilij : 2nd Lieut., In/. R.C 



How does the native intelligence of carpenters compare 

 with that of doctors ? Is there any psychological 

 basis for the division of society into classes ? Is 

 mental retardation ever due to poverty and lack of a 

 chance ? These are questions of vital importance to 

 any theory of social reform, and they are questions 

 which have acquired a new significance as a result of 

 the psychological census taken in the American Army. 

 To classify, conserve, and develop her man-power 

 the army called in those scientists especially concerned 

 with the mind, psychologists and educators, whose 

 privilege it was to examine a large and miscellaneous, if 

 not entirely unselected, sample of the population, and 

 to make a canvass of the country's brain-power such as 

 has never before been taken. Whatever may be our 

 doubts as to the value of the tests in determining 

 individual cases, the summation of their results is both. 



