52 



NA TURE 



[December 15, 1892 



subject would do for botany what Sir H. E, Roscoe has done 

 for chemistry he would confer a great boon on teachers and 

 j'oung students. ^- "■ 



Egyptian Figs. 

 My attention has been celled to a very obvious slip of the pen 

 in my note on Egyptian Figs, in that I have written " Pliny ' 

 instead of " Theophrastus." The former, as all know, was 

 a Latin author, but he simply copies from the latter. Having 

 both authors before me at the time, I accidentally put one name 

 for the others. The refs. are as follows : — Theoph. iv. 2 ; 

 Dioscor. 1. r ; Plin. xiii. 7. George Henslow. 



A Palseozic Ice-Age. 



I CANNOT understand how, when writing on this subject 

 anie,^. loi), I overlooked the circumstance that the ancient 

 boulder-beds of Australia, India, and South Africa received full 

 notice in Prof. J. Prestwich's "Geology," vol. ii. pp. 143-146. 



December 9. W. T. Blanford. 



SCHEELE. 



"TOURING this month Sweden commemorates the one 

 -*-^ hundred and fiftieth anniversary of the birth of 

 one who has conferred an imperishable lustre on her 

 annals. Carl Wilhelm Scheele — although a German by 

 nationality, for he was born at Stralsund, the capital of 

 Pomerania — spent practically the whole of his short life 

 in Sweden, and is usually regarded as a Swede. The son 

 of a tradesman, Joachim Christian Scheele, and the seventh 

 child of a family of eleven, Scheele, as a boy, gave little 

 promise of the genius and power which astonished the 

 scientific world towards the close of the last century. 

 It is perhaps indicative of a certain mental imperfec- 

 tion that he should have been wholly incapable of 

 learning a foreign language ; although he lived in 

 Sweden during more than half his life his knowledge 

 of Swedish was so imperfect that his memoirs, ad- 

 dressed to the Academies of Stockholm and Upsala, 

 were invariably written by him in German and had 

 to be translated by others before publication. By 

 what influences he was led to the study of chemistry is 

 unknown. There was nothing apparently in his home 

 life, or in the mode or circumstances of his education to 

 direct his inclination towards science. As a boy he began 

 the study of pharmacy, and at his own wish was appren- 

 ticed to an apothecary at Goteborg named Bauch, with 

 whom he remained eight years. Here he had access to 

 the standard treatises on chemistry of that time, and he 

 devoted all his leisure, often working far into the night, 

 to the study of the works of Neumann, Lemery, Kunkel, 

 and Stahl. Kunkel's Laboratorium was, indeed, his chief 

 instructor in practical chemistry, and it was by diligently 

 repeating, in the first instance, the experiments contained 

 in that book that he acquired that extraordinary manipu- 

 lative skill and analytical dexterity on which his success 

 as an investigator ultimately rested. 



When twenty-three years of age Scheele removed to 

 Malmo, and some years afterwards to Stockholm, where 

 he superintended the shop of an apothecary named 

 Scharenberg. It was about this time that his career as a 

 discoverer began, by the isolation of tartaric acid from 

 cream of tartar. He ascertained many of the charac- 

 teristic properties of this acid and prepared and ex- 

 amined a number of tartrates. These early efforts met, 

 however, with a somewhat untoward reception. It seems 

 that Scheele drew up an account of his observations and 

 forwarded it to Bergman, who then filled the chair of 

 chemistry in the University of Upsala as the successor of 

 Wallerius. Bergman failed to appreciate the significance 

 of the work of the young and unknown apothecary and by 

 NO. 1207, VOL. 47] 



some mischance the manuscript was lost. The importance 

 of the discovery was, however, recognized by Retzius, who 

 induced Scheele to write a second account of his work and 

 to submit it to the Academy of Sciences at Stockholm, by 

 whomit was eventually printed. In 1771 Scheele published 

 his memorable essay, " On Fluor Mineral and its Acid," in 

 which he first demonstrated the true composition of fluor- 

 spar, showing that it " consists principally of calcareous 

 earth saturated with a peculiar acid," named by him 

 " fluor-acid." Although he found that the " fluor-acid " 

 (hydrofluoric acid) dissolved " siliceous earth," he failed 

 to recognize the change thereby produced in the " fluor- 

 acid " and was thus led to an erroneous conception of its 

 real nature. He was in fact led astray by the circum- 

 stance that his experiments were for the most part made 

 in glass vessels, and hence the fluor-acid was contamin- 

 ated with more or less silica and hydrofluosilicic acid. 

 The origin of the silica in the acid prepared by Scheele 

 was first clearly indicated independently by Wiegleb and 

 Meyer. In 1773 Scheele went to Upsala as pharmaceu- 

 tical assistant to Mr. Lokk, in whose shop he chanced 

 to meet the chemist Gahn. Lokk and Gahn were 

 speculating on the cause of the different mode of 

 action of distilled vinegar on nitre before and after 

 fusion. This was explained by the young assistant, 

 who pointed out the nature of the change eftected on 

 nitre by fusion ; and the fact that it is converted into a 

 salt (potassium nitrite) from which a peculiar acid, differ- 

 ent from true " spirit of nitre," can be obtained by treat- 

 ment with distilled vinegar. Gahn, struck with the sagacity 

 of the young pharmacist, offered to introduce him to 

 Bergman. The invitation was at first declined ; Scheele 

 had not forgotten the unfortunate incident of the tartaric 

 acid memoir. Eventually he allowed himself to be con- 

 vinced that Bergman's action was due more to inadvertence 

 than to indifference, and the acquaintance which followed 

 rapidly ripened into a strong friendship. In 1774 Scheele, 

 at the suggestion of Bergman, published his well-known 

 memoir " On Manganese, Manganesium, or Magnesia 

 Vitrariarum." This essay, although marred and in part 

 obscured by the phlogistic conceptions of the period, will 

 for ever remain one of the classics of chemistry. In it 

 Scheele not only established the nature of " pyrolusite " 

 or " wad," but, in studying the action of acids upon the 

 mineral, he was led to the discovery of baryta and of 

 chlorine, the properties of which he minutely describes. 

 In 1775 appeared his memoir on arsenic acid which he 

 prepared in several ways ; he discovered many of the 

 more striking properties of this body and obtained a 

 number of its salts. In the course of the investigation he 

 discovered arseniureted hydrogen, and the well-known 

 pigment Scheele's Green. In the same year he published 

 his essay on benzoic acid, the " flowers of benzoin " of 

 the apothecary. After a stay of two years in Upsala 

 Scheele was appointed by the Medical College provisor 

 of the pharmacy at Koping, a small town on the north 

 shore of Lake Malar. Instead of the prosperous business 

 he had been led to expect he found nothing but discom- 

 fort and disorder, and the remainder of his life was spent 

 in a constant struggle with privation and debt, relieved at 

 length, to some extent, by a grant, at Bergman's instiga- 

 tion, from the Stockholm Academy. Of this money 

 Scheele set aside one-sixth for his personal necessities, 

 and devoted the remainder to his researches. In 1777 

 he took over the business of the pharmacy from the widow 

 of the former proprietor, but it was only by unremitting 

 industry that he was able to discharge the obligation he 

 thereby incurred Not a year passed, however, without 

 Scheele publishing two or three memoirs, every one 

 of which contained a discovery calculated to enhance 

 his reputation as the greatest experimenter of his 

 time. This untiring devotion to science at length 

 began to tell upon a frame constitutionally weak and 

 doubtless further enfeebled by privation, and by the worry 



