82 



NATURE 



[May 26, 1892 



as to the alcoholic nature of fusel-oil. This conclusion 

 was experimentally confirmed by the conversion of fusel- 

 oil into valeraldehyde. 



Immediately after these experiments, Stas, aided by 

 Dumas, entered on the most important work of his life. 

 It had been already found that on the combustion of the 

 more highly carbonized hydrocarbons the sum of the 

 carbon and hydrogen was decidedly greater than the 

 weight of the substance taken for analysis. Two possible 

 explanations were suggested. The excess might be due 

 to a constant error in the method employed, but on care- 

 ful and frequent repetition of the experiments no such 

 error could be traced ; or there remained the possibility 

 that the composition either of carbon dioxide or that of 

 water had not hitherto been accurately determined. In 

 deciding this question Dumas and Stas developed pre- 

 cautions which had never been equalled, and which cer- 

 tainly have not been since surpassed. 



It must be remembered that, like Darwin in another 

 department of science, Stas was his own most acute and 

 formidable critic. He seems never to have wearied in 

 devising possible objections to his methods and results, 

 nor of suggesting loop-holes through which errors might 

 possibly have crept. In redetermining the atomic weight 

 of carbon, graphite (natural and artificial) and diamonds 

 were submitted to combustion in a current of perfectly 

 dry oxygen. After the checking and re-checking of 

 results, the operators were forced to conclude that the 

 true atomic weight of carbon was lower than hitherto had 

 been universally accepted. It had been determined by 

 Berzelius and Dulong as 12-24. Dumas and Stas made 

 it simply 1 2, and confirmed the result by carefully repeated 

 analyses of many substances of known composition. 

 Hence Dumas was led to accept for the atomic weight of 

 oxygen 16, and for that of nitrogen 14. Whilst Dumas 

 and Boussingault executed their determinations in Paris, 

 Stas carried out the same experiments by the same 

 method at Brussels. 



These startling results recalled the attention of chemists 

 to the hypothesis of Prout, i.e. that the atomic weights of 

 all the elements must be multiples of that of hydrogen 

 (H = I ), by a series of whole numbers. Into this question 

 Dumas and Stas threw themselves heart and soul. The 

 experimenters came to separate conclusions. Stas entered 

 the investigation in the full conviction that he should find 

 the principleof Prout exactly confirmed. At the conclusion 

 of his arduous labours, he found his expectations to be 

 ^' pure illusion." 



On the other hand, Dumas sought to retain the hypo- 

 thesis in a modified form. 



Neither of these eminent researchers seems to have 

 paid sufficient attention to the fact that the atomic 

 weights of a considerable number of the elements differ 

 but very slightly, in excess or in deficiency, from the 

 values which the hypothesis of Prout would require. It 

 is quite possible we are here in presence of a residual 

 phenomenon which interferes with the exactitude of the 

 law. 



In a paper recently read by Prof. W. Spring before the 

 Belgian Academy of Sciences the speaker gave an abstract 

 of the unpublished researches of Stas. In a certain 

 memoir, " On Silver," was discussed a treatise by Dumas 

 on the quantity of gases absorbed by silver, in which 

 Dumas had conceived doubts as to the conclusions of 

 Stas on the hypothesis of Prout. For the critical purpose 

 Stas prepared absolutely pure silver, containing not a trace 

 of gases nor of kindred metals. At the melting-point of 

 iridium the silver was volatilized without revealing by the 

 spectroscope any trace of sodium, a metal which Dumas 

 had suggested as being possibly present. This pure 

 silver gave the same atomic weight as the silver used 

 previously by, Stas. Hence the atomic weight of silver 

 must retain the value which Stas, in his earliest determina- 



NO. I 178, VOL. 46] 



tions, had assigned to it, and consequently the objections 

 of Dumas fall to the ground. 



A second Stas memoir, recently brought to light, fully 

 investigates the question whether the elements sodium, 

 potassium, lithium, calcium, strontium, barium, and thal- 

 lium can be mutually transformed either by intense heat 

 or by electric action. To carry out his experiments, 

 undertaken in consequence of the views lately expressed, 

 that the spectra of the above metals assume a different 

 aspect at very high temperatures, Stas required materials 

 chemically, or rather spectroscopically, pure. This diffi- 

 cult task took him eleven years to accomplish. As a re- 

 sult he found that even at the melting-point of iridium 

 (from 2200" to 2500°) the spectral lines of the metals 

 remained unaltered, and that consequently the trans- 

 mutation of elements under the special circumstance is 

 devoid of foundation. The error may have arisen, as 

 Stas suggests, from the use of materials not absolutely 

 pure. 



In this course of experiments he verified the distinction 

 pointed out by Bunsen between the flame spectra and 

 the electric spark spectra of metals. The flame spectrum 

 of sodium, even at the most intense temperature, shows 

 the well-known double yellow line. But in the complete 

 electric spark spectrum there appear six double lines, 

 lying respectively in the orange red, the yellow, the 

 greenish-yellow, the green, the greenish blue, and the 

 violet. In the solar spectrum all these six double lines 

 are represented by black lines. In the spectruni of the 

 electric arc may be recognized the six double lines, but 

 in the intense white light of the poles merely the flame 

 spectrum with its double yellow line. 



The results of his investigation Stas describes in a 

 discourse entitled " De la Nature de la Lumiere Solaire," 

 delivered in 1891. From the coincidence of the lines of 

 the metals as recognized in the spark-spectrum with 

 Frauenhofer's dark lines in the solar spectrum, Stas in- 

 ferred that the heat and light of the chromosphere were 

 produced by disruptive discharges. 



The daily life of Stas was by no means devoid of 

 troubles. Posts of honour, indeed, were showered upon 

 him both in his own country and abroad. He was Vice- 

 President of the Belgian Sanitary Council, technical 

 assessor of -the National Bank, a perpetual member of 

 the Council of Administrators of the University of Brus- 

 sels, a member of the Statistical Bureau, President of the 

 Belgian Academy of Sciences, Honorary Fellow of the 

 Royal Society (which conferred on him the Davy Medal), 

 Corresponding Member of the French Academy of 

 Sciences, and of the majority of the more distinguished 

 Academies and scientific Societies. So far back as 1873, 

 he was elected an honorary member of the German 

 Chemical Society. He was also a Grand Officer of the 

 Belgian Order of Leopold and of the French Legion of 

 Honour, as well as a knight of many orders throughout 

 Europe. 



His earliest remunerative position was that of Pro- 

 fessor of Chemistry at the Military School of Brussels, a 

 post he successfully filled for more than a quarter of a 

 century. So paltry was the salary attached to this office 

 that he finally petitioned Government for an increase. 

 His request was granted, but in a fashion worse than 

 refusal. He was voted an additional salary of 200 francs 

 —a sum he naturally disdained to accept. Soon after he 

 suff"ered from an affection of the larynx, which put an 

 end to the delivery of lectures. He was compelled to 

 tender his resignation, but as he had not completed the 

 thirty years of service extorted by law he missed his 

 pension. From this plight he was rescued by the offer 

 of a post in connection with the Mint (Commissaire des 

 Monnaies). The respite from trouble was brief. A syn- 

 dicate of speculative capitalists proposed to the Govern- 

 ment to coin an enormous sum of francs. With the full 



