SOME THINGS CHEMISTRY CANNOT DO.

Oamaru Mail, Volume XXXIX, Issue 10777, 27 May 1911, Page 3 (Supplement)

SOME THINGS CHEMISTRY CANNOT DO.

It is doubtful which variety of citizens seems most hopeless to the scientific man —the one who denies that science can tell us anything, or the one who' believes blindly that it can-do everything. '-The last few years, writes Dr "William Eiclißo.ltz, . in TJeber Land und have-'emnched' science and technology ,with';discdveriesr&<i. indentions of the most sensational character. It is not surprising, he says, tli'at c generation which;' Has', witnessed. Me discovery of Rontgen: rays and radium, and the development yof wireless tele- ' graphy, airships; , and \ aeroplanes, should become and refuse to-ibe greatly impressed-by anything. . • Ihe brilliancy of thenew.d.iscoyeries cafets into the .shade ' previous, years ;of jx>il and the numberless main unsolved; ,Wo quote .below: from an abstract of: 13r Eicliholtz's article made for the Scientific American Supplement. We .read':/ <"Maay persons. : are , surprised whjjn they are to{clvilis' 'itr-ls. some cases, t'o detect adulteration:, pf food, and can scarcely :believe : ; that science is still, so. impotent. j Most ■'articles of food- 'rJaferiaV''prtfaucfs aottd . consist mainly 'of the very cdjnplex ganic substances. "When it islexplaiiiSd that we do not know the chemical stiver ture of albumen, ;themostimportai(t constituent of every animal and vegetable . cell, and that most;.of thesubf ; stances: which. give .foodstuffs their " characteristic flavors and caiiijgt even be chemically' 'definedy. 'it : ni"ay:'" be, understood '.why. the "chemist' findsiyt ' very difficult, .and often impo'sSiblejjflo distinguish pure from' adulterated .wi&Jei or genuine frdmartificial butter., "The statement that we do ript;kiioj(V the chemical structure of albumen, does not mean that we are entirely ignorant of the composition of albumen,. We know that albumen contains certain chemical elements, combined in. certain proportions,but this knowledge does not give a'mental picture of the structure of the albumen molecule. . . . "The chemical investigation, of naju-. ral products is made more difficult ;.by the almost invariable association ofea number of similar and nearly related 'homologous' compounds. Butter,. for , example, contains a long series of fatty acids, which shade into other so actually that the series can only be :re r solved into a number of groups whipli defy analysis'into their individual members." Fruit juices similarly contain series of organic acids". . v . ""The systematic methods of inorganic, analysis are, therefore, inapplicable ,to organic bodies aii<l tli© reproach. cflst upon food analysis has very little jus-, tification, for it is not, and it newer will be, possible to determine the ingredients of animal and ducts by. the rigid system and with tfie absolute certainty with which a skilled chemist can analyse the most complex of inorganic substances." In many cases, the writer goes on to -,ay, the falsification of food products •an be detected only through some; unmportant ingredient which happens to iroduce a striking reaction, such as the nicroscopic grains of pollen contained n honey. If these are absent, the Genuineness of the honey may be doubtid, but, unfortunately, ' the adulieTators now mix artificial 'rains with;their'artificial Koney. The inalysis of wine "is still more difficult, some mixtures sold as wine contain riot i'drop of grape juice, yet defy detecion by chemistry. : "The consumer, however, cares -nothing for chemical indentity. He risbes to kliow the source of his food,, mt in this inquiry the chemist is re-. tricted to limits fixed' by nature. Hi »ne instance these limits have recently ieen transcended, but not: by tlie ■hemist. The nice discrimination between varieties of albumen winch '.hemistry is unable' to make* has been >rilliantly accomplished •by biological cience. • "If an extract; of horse fiesii, or ;]ie serum of horse blobd, is injected •epeatedly during a considerable period nto the circiilation' of a. : rabbit, a. itance called; antitoxin, which ,P r wm- . ates the albumen. of horses, andthnt, ilone, is formed in the blood' of the •abbit. 'Hence, if the * serum of-sthe : 'abbit which, has been thus„ treated ;s nixed with an extract made from suspected meat, the presence ?f horse--lesli in the meat will, be indicated by ;he formation of a precipitate. _.lhis nethod is already extensively employed ; or : the detection of horse-flesh in saulages: '-M antitoxin which -preciptates ium'an ; albumen alone, ; and \vhich : is iseftil for the detection of human blood n the..investigation: of crimes, ' is- prepared) by a very .similar "This biological reaction; which w sailed Uhlenhuth's reaction, from the lame of its discovered, is distinguished from most 1 ' chemical reactions by its leli.cacy anfl;iprecision. It can be apilied with success to exceedingly small lliaiitities of matter. . . .. ; "Technical problems which are ; not >f chemical nature arc usually accornianicd by their solutions on their first ippearance. ' . • "The necessity of travelling 60 miles in hour was hot felt until lpng after ih'e steam engine had .been invented. siicli wants iire rather, •suggested, and ilowly, impressed upon conservative nlfc. nahity, tlie existence of applying them. Hence technical -, in'entions are thankfully received as. un-. jxpected : gifts, 'while dis:overies are regarded as long deterred layments .of s just- dues: There are :eptions, "' however, to 'both' of these rules.The " : probl'em of : flight lias ociupied huinanity for thousands of years md,: on the other hand, synthetic iheinistry: has given us medicines, dye;tuffs, and other substances which have fecome : 'indispensable, although they occur nowhere in_ nature, but nere :reated in,-the,chemical laboratory."