98 REPORT— 1894. 



and stinking fumes. . . . Whencesover this stinking smoak proceeded, so in- 

 Hammable 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.' ' 



And again : ' We took a clear glass vial, capable of containing three ounces of 

 water, with a long cylindiical neck ; this we Ulled Avith oil of vitriol, and fair 

 water, of each a like quantity, and casting in six small 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. . . . And soon after we per- 

 ceived 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 

 Fubstance 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 foinier 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 im- 

 prisoned substance readily 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 could be made artificially in many ways, but 

 could not be caught and 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 touching the Relation betwixt Plame 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 flashes could be 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 brim- 

 stone, which lasted so very long we could not but wonder at it ' ; and fulminating 

 gold detonated tn vacuo when heated by a burning glass, or when dropped on 

 heated iron. Gunpowder 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, though our mixture burns under water, yet it does not burn without air, 

 being supplied with enough to serve the turn by the numerous eruptions of the 

 aereal particles of the dissipated nitre.' However, he * removes this suspicion ' by 

 obtaining nitre crystallised in vacuo. He then suggests the possibility of the nitre 

 supplying ' vehemently agitated vapours ' which are no true air, but being exceed- 

 ingly rarefied by the fire ' emulate air.' Boyle never grasped the true function of 

 air in combustion. From his later experiments on the calcination of metals he 

 drew the same conclusion that we find in the ' Sceptical Chemist,' namely, that 

 igneous particles combine with other corpuscles to form new bodies. And yet he 

 saw there was a real connection between air and fire. In his tract on Artificial 

 Phosphor! Boyle showed that a piece of phosphorus sealed up in a glass vessel 

 gradually lost its light. ' It seems,' he wrote, ' that the air included with the 

 phosphorus either had some vital substance preyed upon thereby, or else was tamed 

 by the fumes of the phosphorus and rendered at length unfit to continue the 

 particular flame of our noctiluca.' 



The genius of Robert Hooke was in sharp contrast with that of Boyle. 



' ' On the Difficulty of preserving Flame without Air,' 1672. 



^ 'Gas, vasis incoercibile, foras in aerem prorumpit.' — Ortus Medicines. The 

 epithet ' sylvestre ' was applied by Van Helmont to all artificially prepared gases. 

 He meant by it ' untameable ' and ' non-condensible ' — ' quod in corpus cogi non 

 potest visibile.' 



