Jan. 29, 1 8 74 J 



NA TURE 



245 



was not one of the least obstacles which stood in the way 

 of continuous researches. Thus chemists and physicists 

 have eagerly sought to discover a regular process of pre- 

 paration, or at least a method of obtaining appreciable 

 quantities of ozone. M. Houzeau, who has devoted much 

 of his time and talents to the study of ozone, has recently 

 devised an apparatus which is spreading rapidly among 

 the laboratories, and which has already yielded very 

 remarkable results, of which the following is a brief 

 rhiDiic. 



The apparatus of M. Houzeau consists of two concen- 

 tric tubes, the middle one enclosing a metallic wire, fixed 

 to one extremity of a Ruhmkorff coil ; the other wire, 

 attached to the second pole of the coil, is rolled spirally 

 round the exterior tube ; finally, the gas circulates in the 

 annular space comprised between the interior and exte- 

 rior tubes, and, consequently, is not directly in contact 

 with either cf the two wires. The two metallic wires, 

 along which the electricity flows, play the part of a Leyden 

 jar, and the gas which circulates in the space traversed 

 by the dark etilluvia, by means of which the two different 

 electricities shot along the wires are re-united, is essen- 

 tially modified. If it be oxygen, it is charged with a 

 notable quantity of ozone, whose odour rapidly spreads 

 around the apparatus. 



M. Houzeau's method produces oxygen much more 

 charged with ozone than any otlier process ; thus it has 

 enabled some new properties of the gas to be discovered. 

 Let the gas issuing from the effluvia-tubes come into con- 

 tact with olefiant gas and the latter will be immediately 

 set on fire with a loud explosion. M. Houzeau has de- 

 vised a beautiful experiment, by introducing gradually 

 into a somewhat large tube, a current of bicarburetted 

 hydrogen, obtained by the reaction of sulphuric acid on 

 alcohol ; then by means of another narrower lube, pene- 

 trating about a centimetre into the tube filled with ethy- 

 lene, he directs very gently a current of ozone, condensed 

 as much as possible ; the ozone which is introduced causes 

 detonation. 



When ozone is made to act on benzine a product is 

 obtained, which, according to M. Houzeau, is essentially 

 detonating ; this ozo-bcnzine under concussion or pres- 

 sure disengages suddenly a considerable quantity of gas, 

 as do nitro-glycerinc or the picrates, whose fulminating 

 properties are well known. A few decigrammes of ozo- 

 benzine produce a detonation so violent that the windows 

 of the laboratory arc invariably broken, and thus only the 

 very smallest quantities should be used in experiments ; 

 3 to 5 milligrammes suffice to establish the eminently ex- 

 pIosi\e properties of this dangerous substance. 



M. Houzeau has also been able to show by means of 

 his apparatus, the remarkable decolourising properties of 

 ozone. If a solution of indigo is thrown into a bottle 

 containing oxygen mixed with ozone, it is as easily de- 

 prived of its colour as if it were in contact with chlorine. 

 It is known, moreover, that dyed stufl's are bleached by 

 being simply exposed to the air, and as it is now proved 

 that our atmosphere contains ozone, it appears very 

 probable that it is this gas which is the active agent in 

 the old process of bleaching on the grass. 



Such are the new properties which M. Houzeau has 

 been able to establish by employing ozone in a state of 

 condensation infinitely greater than that which is pre- 

 sented when it was prepared by the old methods ; and 

 these results are certainly not the only ones which may 

 be looked for. 



M. Houzeau is not the only one who has made use of 

 the tubes whose structure he has made known, and 

 soon we may expect to see them modified so as to make 

 them much more durable. M. Boillot, a writer well 

 known to the readers of the Monifcii?; proposes to 

 substitute for the wire of M. Houzeau's tube, whalebone 

 charcoal contained in the interior tube and in the space 

 comprised between the gas-holding tube and a thin tube 

 concentric with the first two : and M. A. Th^nanl has 



brought to bear on the construction of the tubes a further 

 modification which makes them still more efficacious. 



As is shown in Fig. i. M. A. Thc%ard's apparatus is 

 composed of three tubes of unequal length, welded to- 

 gether. The central tube aa' is filled with chloride of an- 

 timony in solution with hydrochloric acid ; the negative 

 pole B of the coil dips in the liquid which descends 

 to the bottom of the tube at a'; the same solution of 

 chloride of antimony is placed in the exterior tube E ; it 

 I'eceives the positive wire of the coil at A. The liquid E E 

 is then positively electrified, the liquid aa' negatively, and 

 the gas which enters at C and issues at D, after having 

 passed across the annular space between the two tubes, 

 is submitted to the electric effluvia determined by the 

 two opposite electricities of the two liquids. 



Into the tubes thus arranged M. A. Thenard directs 

 the gases on which he wishes the electric effluvia to act. 

 One of those which he first submitted to this treatment 

 was carbonic acid, which is decomposed in oxygen and 

 carbonic oxide, with increase of volume. The experi- 

 ment is perfectly clear, and such as to show the complete 

 difference between the action of the effluvia and that of 

 the spark. While carbonic acid submitted to the 

 decomposing power of dark discharges contains about 

 one-fourth of its volume of the mixture of oxygen and 

 oxide of carbon, which proceeds from its decomposition, 

 carbonic acid decomposed by the luminous sparks of a coil 

 never yields more than 7'5 per cent. ; for the latter act 

 not only by their decomposing power, but also by their 

 heat, which determines the combination of the gases as 

 first separated, up to the moment when carbonic acid, 

 o.xygen, and carbonic oxide, are formed in such a state 

 of equilibrium, the spark produces no further effect, the 

 decomposition being equal to the combination. This 

 equilibrium is reached when the mixture contains pre- 

 cisely 7'5 per cent, of carbonic oxide. 



This experiment is not, however, the most curious of 

 those which have been published during the course of 

 last year by MM. Paul and A. Thenard working together 

 in that laboratory in the place Saint-Sulpice, which is so 

 liberally opened to all who wish to study. 



M. Paul Thenard has noticed that marsh-gas sometimes 

 contains equal volumes of carbonic acid and protocar- 

 buretted hydrogen, i.e., it constitutes a mixture in which 

 the carbon, the hydrogen, and the oxygen are found in 

 equal quantities, as when they are combined in a very 

 largely diffused organic matter — glucose. Has the efflu- 

 vium the power of determining the union of these diffe- 

 rent elements, so as to reconstitute an organic substance? 

 Such was the idea which M M. P. and A. Thenard wished to 

 verify by making a mixture in equal quantities of formic 

 acid and carbonic acid in one of their effluvia tubes, so 

 arranged that the changes of volume which the gases 

 may undergo are easily determined. 



After ten minutes, the condensation of the gases was 

 already sensible ; it increased in time, and soon there 

 was seen to appear upon the sides of the tubes a 

 liquid possessing a strong refracting power, viscous, 

 yellowish, which was found to be an organic sub- 

 stance of a somewhat high order, burning readily. Its 

 nature has not been determined, but it is sufficient to 

 prove the importance of MM. Thcnard's expEriment, that 

 its formation has been established. 



The synthesis of organic matters from the elements 

 has always been one of the problems which profit- 

 ably engage the attention of chemists ; and vegetation, 

 indeed, enables us to witness their formation by a series 

 of reactions which we cannot reproduce in the laboratory. 

 Is it not surprising, for example, that under the influence 

 of light a leaf can decompose carbonic acid and water, 

 both extremely stable substances, and which we can only 

 reduce to their elements by means of the most elevated 

 temperatures which we can produce ? But this work 

 which is accompHshed in the leaf of a plant, the effluvium 

 perform.s equally well ; it decomposes water into oxygen 



