350 



NA TURE 



[August 9, \ 894 



sulphur, or mercury, much less all the three. Gold is the 

 most obvious instance. It may be heated for months in a fur- 

 nace without losing weight or altering in character, and yet one 

 of its supposed constituents is volatile and another combustible. 

 Neither can water or solvents separate any of the three princi- 

 ples from gold ; the metal may be adje,i to, and so brought 

 into solution and into crystalline compounds, but the gold 

 particles are present all the time ; and the metal may be reduced 

 to the same weight of yellow, ponderous, malleable substance 

 it was before its mixture." He points out the confusion which 

 earlier chemists had made between calcination in the open air 

 and distillation in retorts ; he shows that in compounds, e.f;. 

 copper nitrate, the particles retain their nature, although dis- 

 gui'ied, in the combination, for the nitric acid may be separated 

 by heat, the copper by precipitation. Bat the sceptical chemist, 

 though pouring ridicule on the Iria prima, could not but admit 

 the power of water to produce organic substances. He quotes 

 Van Helraont's famous experiment of growing ashoot of willow 

 in baked earth moistened with distilled water, and he repeats 

 the experiment in various forms. Ignorant of the existence of 

 carbonic acid in the air (discovered a century later by Black), 

 he is driven to conclude that the plant is fashioned out of the 

 pure water. But he rejects the doctrine — .is old as Thales and 

 as modern as Van Helmont — that water is the foundation of all 

 things. M. de Kochas had publi-hed a remarkable experiment on 

 water. By artificial heat, by graduations of coagulations and con- 

 gelations, he had turned it into earth which produced animals, 

 vegetables, and minerals. The minerals began to grow 

 and increase, and were composed of much salt, little sulphur, 

 and less mercury ; the animals moved and ate, and were com- 

 posed of much sulphur, little mercury, and less salt. " I have 

 some suspicions," says Boyle, "concerning this strange rela- 

 tion ; though as for the generation of living creatures, both 

 vegetable and sensitive, it need not seem incredible, since we 

 find that our common water, which is often impregnated with a 

 variety of seeds, long kept in a quiet place, will putrefy, and 

 then, too, produce moss and little worms according to the 

 nature of the seeds that were lurking in it." 



I will give two short quotations from the " Sceptical 

 Chemiii," which show the author at his best and his worst. 

 In the first he is discussing the nature of chemical combination 

 between elementary particles: "There are clusters wherein 

 the particles stick not so close together, but they may meet with 

 corpuscles of another denomination, disposed to be more 

 closely united with some of them than they were among 

 themselves ; and in .such case two corpuscles thus combining, 

 losing that shape, size, or motion upon whose account they 

 exhibited such a determinate quality, each of them really 

 ceases to be a corpuscle of the same denomination as 

 it was before ; and from the coalition of these there may 

 result a new body, as really one as either of the corpuscles 

 before they were confounded. ... If you dissolve minium 

 in good spirit of vinegar and crystallise the solution, you 

 shall not only have a saccharine salt exceedingly dilTcrent from 

 both its ingredients, but the union is so strict that the spirit of 

 vinegar seems to be destroyed . . . for there is no sourness at 

 all, l)ut an admirable sweetness to be tasted in the concretion." 

 Id this passage we can distinctly see the germ of the modern 

 theory of chemical affinity unitmg atoms into chemical com- 

 1«uikIs. In the second quotation Boyle is arguing that fire is 

 nit 'nly .in analyser of mixtures, but compounds the ingredients 

 of Lilies after a new manner ; mercury, for instance, may be 

 lurnc'l into a liquid, from which the mercury cannot he re- 

 iluccd again, and consequently is more than a "disguise" of 

 it. "Two friends of mine," he says, "both of them persons of 

 aniuspected credit, have solemnly assured me that after many 

 trials they m.ide to reduce mercury into water, they once, by 

 several cohob.itions, reduced a pound of quicksilver into almost 

 a pound of water, and this without the addition of any sub- 

 stance, but only by urging the mercury with a fire skilfully 

 maoaged. Hence it appcirs that by means of fire we may obtain 

 from a mixed body what did not preexist therein." Boyle has 

 •ometimes been charged with credulity, and chemists who know 

 how mercury has a way of disappearing without leaving even its 

 weight of water lichiml will smile to hear that the persons of 

 unsuspected credit res|x)nsible for this experiment were " the 

 one a phy.ician, the other a dislinguishcil mathematician." 



Boyle's writings contain the record of numerous important 

 chemical otiservations, e.g. the synthesis of nitre, and the pre- 

 {wration of nitric acid by the distillation of nitre with oil of 



NO. 1293, VOL. 50J 



vitriol. He discovered several of the delicate tests we still use, 

 c.;;. solution of ammonia as a test for copper, silver nitrate as 

 a test for chlorides, gallic acid .is a test for iron. But I wish 

 especially to refer to the work done by Boyle on the air and its 

 relation to combustion. The air, according to him, was com- 

 posed of three dilTerent kinds of particles : (I) exhalations from 

 water and animals ; (2) a very subtle emanation from the earth's 

 magnetism, which produces the sensation of light ; and (3) a 

 lluid compressible and dilat.ible, having weight, and able to 

 refract light. It is this third portion of air which plays an 

 active part in many chemical operations. Like Van Helmont, 

 Boyle recognised differences in gases, but did not distinguish 

 them as being something different in kind from air. He pre- 

 pared hydrogen by the action of hydrochloric and sulphuric 

 acids on iron, but his chief concern w.is to show th.it the new 

 gas was compressible and w.is dilatable by heat ; in other words, 

 that it was really air. His observations are worth quoting ; 

 they contain, I believe, the first undoubted description of 

 hydrogen, and the first method devised for collecting and 

 examining freshly prepared gases. 



" Having provided a saline spirit . . . exceedingly sharp and 

 piercing, we put into a vial a convenient quantity of tilings of 

 steel, purposely filed from a piece of good steel. This metal- 

 line powder being moistened with the menstruum was after- 

 wards drenched with more, whereupon the mixture grew very 

 hot, and belched up copious and stinking fumes. . . . Whence- 

 soever this stinking smoak proceeded, so inflammable was it, 

 that upon the approach of a lighted candle it would readily 

 enough take fire, and burn with a blewish and somewhat 

 greenish flame at the mouth of the viol ; and that, though with 

 little light, yet with more strength than one would' easily 

 suspect."' 



.■Vnd again : " We took a clear glass vial, cap.ible of contain- 

 ing three ounces of water, with a lon'^ cylindrical neck ; this wc 

 filled with oil of vitriol, and fair water, of each a like quantity, 

 and casting in six suiall iron nails we stopped the mouth of the 

 glass, and speedily inverting it, we put the neck of it into a 

 wide-mouthed glass with more of the same liquor in it. . . . 

 .\nd soon after we perceived the bubbles, produced by the 

 action of the menstruum upon the metal, ascending in swarms ; 

 by degrees they depressed the liquor till, at length, the substance 

 contained in these bubbles possessed the whole cavity of the 

 vial. And for three or four days and nights together the cavity 

 of the glass was possessed by the air, since by its spring it was 

 able for so long a time to hinder the liquor from regaining its 

 former place. Just before we took the vial out of the other 

 glass, upon the application of the warm hand to the convex part 

 of the glass, the imprisoned substance re.idily dilated itself like 

 air, and broke through the liquor in several succeeding 

 bubbles." 



The importance of this experiment will be evident when we 

 consider that Van Helmont had declared that gases coulil be 

 made artificially in many ways, but could not be caught .in.l 

 held in vessels.- 



Armed with the air-pump which he had so greatly improved, 

 Boyle in 1660 began many experiments on combustion, which he 

 afterwards published under the title " New Experiments touch, 

 ing the Kelation betwixt 1-lame and Air." In these researches 

 he shows that sulphur will not burn when the air is removed. 

 The sulphur was lowered on to a hot iron plate in a receiver 

 made vacuous by the pump ; it smoked, but did not ignite. On 

 allowing a little air to enter "divers little ll.ishcs could he 

 seen " : these were extinguished on sucking out the air again. 

 A candle flame and a hydrogen flame under a receiver were 

 gradually extinguished when the air was pumped away. On 

 the other hand, on dropping gunpowder on to a hot iron plate 

 in vacuo there appeared " a broad blue flame like that of 

 brimstone, which lasted so very long wc could not but wonder 

 at it " ; and fulminating gold detonated i'« -aiiio when heated 

 by a burning glass, or when dropped on heated iron. Gun- 

 powder also he found to burn under water. He is driven to the 

 conclusion " that flame may exist without air." But it may be 

 supposed that air is mechanically enclosed in the crystals of 

 nitre—" in its very formation the corpuscles may intercept store 

 of little aereal particles. . . . According to this surmise, 



' On the DilTiculty ofprcjcrving Flame witliout Air,' 

 'Gas, vasis incoercible, loras in acre m proriuniut." 



167a. 

 -Ortiis MidictHa. 



The epithet •■ sylveslrc " wai applied by Van Helmont 10 all artificially pre. 

 pared gasc lie mc-int by il " unl.imeable " and " non-condemiblc — 

 '* ((uod in corpus cojri non potc»t visibiie." 



