"Errors 



Eruption 



SCIENTIFIC SIDE-LIGHTS 



220 



stance without diminishing its weight, but 

 whose subtraction actually added to the 

 weight. It is the great merit of Lavoisier 

 that he ... was the first to see clearly 

 that, in every chemical process, increase of 

 weight means increase of material, and loss 

 of weight loss of material. Iron, in rusting, 

 gains in weight. Hence, said Lavoisier, it 

 has combined with some material. No, said 

 the defenders of the phlogiston theory such 

 men as Cavendish, Priestly, and Scheele it 

 has only lost phlogiston. You are making too 

 much of this matter of weight. Phlogiston 

 differs from your gross forms of matter in 

 that it is specifically light, and, when taken 

 from a body, increases its weight. We smile 

 at this idea, and we find it difficult to be- 

 lieve that these men, the first scientific 

 minds of their age, could believe in such ab- 

 surdity. But we must remember that the 

 idea did not originate with them. It was a 

 part of the old Greek philosophy, and from 

 the pages of Aristotle was taught in every 

 school of Europe until within two hundred 

 years; and, even in our own time, we still 

 hear of imponderable agents. Text-books of 

 science are used in some of our schools 

 which refer the phenomena of heat and elec- 

 tricity to attenuated forms of matter, that 

 can be added to or subtracted from bodies 

 without altering their weight. Such facts 

 should teach us, not that we are so much 

 wiser than our fathers, but that our famil- 

 iar ideas of the composition of matter are 

 not such simple deductions from the phe- 

 nomena of Nature as they appear to us ; and 

 this discussion of the evidence, on which 

 these conclusions are based, is therefore by 

 no means superfluous. COOKE New Chemis- 

 try, lect. 5, p. 112. (A., 1899.) 



1072. 



The Imagined 



" Phlogiston," the Principle of Fire. They 

 [ancient philosophers] termed the principle 

 of fire phlogiston, and burning, or the escape 

 of fire, dephlogistication, and their ingenious 

 system did not a little to retard the progress 

 of truth. The philosophers of that age 

 either took no account of the increase of 

 weight which results from burning, or at- 

 tempted to explain the few instances in 

 which the fact was forced upon their atten- 

 tion by the fanciful notion of Aristotle 

 that the essence of fire was specifically light. 

 Hence, they reasoned, phlogiston buoys up 

 all bodies into which it enters, and after its 

 escape in the process of burning, the burnt 

 material must weigh more than before. It 

 was not until 1783 that the true theory of 

 combustion was discovered, and from this 

 discovery modern chemistry dates. The for- 

 tunate discoverer was Lavoisier. He proved, 

 by simply weighing the products of combus- 

 tion, that burning, instead of being a loss of 

 phlogiston, is a union of the burning sub- 

 stance with the oxygen of the air, and this 

 theory is now one of the best established 

 principles of science. COOKE Religion and 

 Chemistry, ch. 3, p. 78. (A., 1897.) 



1O73. Theories Aban- 

 doned by Sir William Herschel Change 

 upon Evidence Honest Avowal of the 

 Change The True Scientist Seeks Fact and 

 Truth. [Herschel] wrote thus in 1802, sev- 

 enteen years after he had enunciated the 

 cloven-disk theory [which regards the sidere- 

 al universe as a cloven disk, which w r e look 

 through edgewise in the Milky Way] : " Al- 

 tho our sun and all the stars we see may 

 truly be said to be in the plane of the Milky- 

 Way, yet I am now convinced by a long in- 

 spection and continued examination of it, 

 that the Milky Way itself consists of stars 

 very differently scattered from those which 

 are immediately about us." And again in 

 1811 he said: "When the novelty of the 

 subject is considered, we cannot be surprised 

 that many things formerly taken for granted 

 should, on examination, prove to be different 

 from what they were generally, but incau- 

 tiously, supposed to be. For instance, an 

 equal scattering of the stars may be ad- 

 mitted in certain calculations ; but when we 

 examine the Milky Way, or the closely com- 

 pressed clusters of stars, this supposed 

 equality of scattering must be given up." 

 PROCTOR Expanse of Heaven, p. 260. (L. G. 

 & Co., 1897.) 



1074. 



Theory Not a Safe 



Guide for Vital Processes Bone-soup of 

 French Academy. There are other juices 

 besides the albumin; these are the most im- 

 portant of the flavoring constituents, and, 

 with the other constituents of animal food, 

 have great nutritive value; so much so 

 that animal food is quite tasteless and al- 

 most worthless without them. I have laid 

 especial emphasis on the above qualification, 

 lest the reader should be led into an error 

 originated by the bone-soup committee of the 

 French Academy, and propagated widely by 

 Liebig that of regarding these juices as a 

 concentrated nutriment when taken alone. 

 They constitute collectively the eaetractum 

 carnis, which, with the addition of more or 

 less gelatin ( the less the better ) , is com- 

 monly sold as Liebig's " Extract of Meat." 

 It is prepared by simply mincing lean meat, 

 exposing it to the action of cold water, and 

 then evaporating down the solution of ex- 

 tract thus obtained. WILLIAMS Chemistry 

 of Cookery, ch. 3, p. 25. (A., 1900.) 



1075. 



The Theory of Cat- 



astrophism in Geology. Cuvier imagined 

 that the whole history of the earth's crust, 

 since the time when living creatures had 

 first appeared on the surface, must be di- 

 vided into a number of perfectly distinct 

 periods, or divisions of time, and that the 

 individual periods must have been separated 

 from one another by peculiar revolutions of 

 an unknown nature (cataclysms, or catas- 

 trophes). Each revolution was followed by 

 the utter annihilation of the till then exist- 

 ing animals and plants, and after its ter- 

 mination a completely new creation of or- 

 ganic forms took place. A new world of 



