36 VIII.-Observations on the Solution of Gases in PVattv. December 16th 1869. Dr. Williamson President in the Chair. THEREbeing no formal papers befDre the Society on this occa- sion the President requested Mr. McL eo d to comniunicate the result of his observations on the Gdscs in Sea-water. Mr. McLeod alluding to the opinion which appears to be entertained by some persons that sea-water taken from great depths effervesces when broiight to the surfdce expressed his belief that this idea is quite erroneous. hIr. Hunter in his recent experiments on sea-water taken from great depths found only 2.8 volumes of gas in lOO volumes of the watx a quantity much less than that coiitaiiied in orciinary Thames water which as every body knows does not effervesce when drawn from a tap.He (Blr. RlcLeocl) had lately mzde some experimeiits 011 the quantity of gas contained in Thamnes water whicli had been kept in a cistern and drawn from a tdp; 100 volunies of this water were found to coiitaiii-Volumes. Nitrogen ................ 1.398 oxygen.................. 0-619 Carbonic anhydride. ....... 4.180 Total.. ........ 6.197 As however the qnantity of gas dissolved in sea-water may be affected by the presence of the sdine constituents lie had also experiineiited on a sample of sea-water collected near Worthing which had been exposed to the air for 21 inonths-at least kept in a half-filled bottle-and had probably therefore taken up as much oxygen and nitrogen as it was capable of holding. 100 volumes of this sea-water were found to contaiii- Volumes.Xi trogeii ................ 1*lo4 Oxygen. ................. 0.572 Carbonic anhydride. ....... 2.620 rrotRi.......... 4-29G SOLUTION OF GASES IN WATER. Thisis a much larger quantity than that found by Mr. Hunter viz. 2.8 volumes in 100 whenie it may be inferred that sea- water taken from great depths is very far from being saturated with gases and caniiot therefore exhibit any tendency to give off gas when brought to the surhce." The President remarked on the importance of attending to the effect of soluble matter in water or its power of holding gases in solution. He then called on Dr. Hugo Miiller to communicate his observations on the condition of carbonic acid gas when dissolved in water.Dr. Hngo Miiller said that in mzking some experiments in connection with the manufacture of soda-water he had found that in order to mske the water take up carbonic acid gas in such a manner that the gas may not be immediately disengaged when the liquid is let out of the apparatus it is necessary that the gas and water be left together in the apparatus for at least 24 hours. If the agitation is continued merely for an hour or an hour and a-half then on letting out the water the car-bonic anhydride iristaiitly disengages itself the water becomes creamy the gas comes np immediately and the effervescence * Since the above remarks were made Mr. Ilunter's paper has been printed and on carefully examining his numbers (which was scarcely pobsible when the communi- cation was read) it will be seen that the comparatively small quantity of gas which he obtaiued from the sea water was accounted for by the f~ct that a much smaller amount of carbonic anhydride was obtained by him than from the water co.lected at Worthing though the quantities of nitrogen and oxygen were conaiderably larger.The large& proportions 3f nitrogen and oxygen were obtained by Mr. Huuter from water collected on July 27th from a depth of 450 fathoms the temperature of the water at tl at depth heing 47O.6 F (SC.l C.). This contained in 100 volumes 1-457 vols. of nitrosen and 0,021 of oxy:en (the sitme quantity of oxygen but less nitrogen was also cbtailred from a depth of 500 fathoms on July 23rdi and would therefore be-in to evolve gas at a temperature of 14O.6 C.that is ifnitrogen is soluale In sea-water to the s'ime extent as in distilled water. This quite accords with Mr. Hunter's statement that the water contained so much gas that it began to evolve it on a slight elevation of temp1,rature. In the case of the water from Worthing no precaution mas taken to saturate it with air it tieing me:ely left,as stated iu a partially filled bottle. If it had actually absorbed as mlrch nitrogen as it was capable of retaining it would appear that this gas is more soluble in distilled than in sea-water.-H. M. Mr. Hunter in a letter to the Edit,or relating to this matter says that he is not aware of any ofiicial statement having been made that sea-water brought up from great depths effervesced lile sodn-Nater.Mr. W. L. Caipetiter who acrompanied the expedi&n on the first cruise told him that he could not uiiderstalrd hdw the misrake arose as he had never observed ang such phenomenon. Tlie waters examined by Mr. Hunter on board H.U.S. ''Porcupine,'' did not of course exhibit any tendency to give off gas till they were heated. OBSERVATIONS ON THE is over; mhereae if the gas be allowed to remain in contact with the water from 20 to 24 hours and the liquid be then let out the carbonic anhydride diseiigages itself from the water gradually and attaches itself to tho sides of the glass seeming indeed to be altogether in a different state to that in which it is after being left for only a short time in contact with the water.It aypears indeed that in the one case that is after a short contact tile carbonic anhydride dissolves in the water merely as such but that after prolonged contact it becomes hydrated and is dissolved by the water as hydrogen carbonate or cfirbonic acid and is tlien retained more firmly. Dr. Miill er mentioned also another observation which he had made in connection with this subject iiamely that on putting a very small quaiitity of conimoii salt into the apparatus to-gether with the water which is to be carbonsted the whole process of dissc Jution takes place much more quickly the accelera- tion being probably due to decomposition of the sodium chloride by carbonic acid hydrochloric acid being formed together with hi-carbonate of soda.He could not say positively whether the whole of the chlorine present is thus set free as liydrochloric acid but he had ascertained the presence of that acid by means of ultramarine which is known not to be acted upon by car- bonic acid or by sodium chloride but is acted upon by the carbonated water made in the way just described. The libera- tion of an acid in this reaction may therefore be inferred. In coniiection with this subject it may also be mentioned that on passing carbonic acid gas through a neutrar or even slightly acid solution of chloride of lead a turbidity is produced after a short time but not immediately. In a certain time indeed a precipitate is formed consisting of the double salt of carbonate and chloride of lead.This compouiid is also found in nature and indeed the reaction just noticed seems to explain the circumstauce that in nature we never find pure chloride of lead except as a sublimate in volcanoes. In all other cases the chloride of lead is found associated with carbonate forming the mineral called ‘‘ chloro-carbonate of lead,” and there is no doubt that this salt being formed in nature by an aqueous process the ever present carbonic acid has partly decomposed the chloride of le td and formed this chloro-carbonate. This is another instance in which a chloride is decomposed by car-bonic acid and there can be no doubt that this decomposition is of frqiient occiirrence. SOLUTION OF GASES IN WATER. 39 Dr. Divers observed that on nixing rectified spirit with ordinary distilled water.which contains air from having uncler- gone exposur3 there is a kind of effervescence the liquid Fe- coming milky just as if a precipitate were forming. Tliis effect is due to the libercttim of extremely mimite hbbles of air and seems to show that the mixture of spirit and water has less solvent power for air than for water itself. The President said that it would be interesting to know whether the temperature has any connection with the peculiar stctte observed by Dr. Miiller in the dissolved carbonic acid more especinlly as the receiit experiments of Dr. An drews cn the liquefiction of carbonic acid at different temperatures have shown that a few degrees of temperature make a very great difference in the properties of the carbonic acid-a difference of property not to be overcome by multiplying the pressure enor-mously.Dr. Miiller's observations on the greater solubility of car-bonic acid in water containing sodic chloride appeared to him (the President) to be of considerable theoreticdl vdlue more especially when confirmed as they were by his observation upon ultr.amariue when used as a test for free hydrochloric acid. In connection with this subject he drew atteiitioiz to the conclusion at which he had himself arrived some time ago respecting the state iii which salts such as sodic chloride dissolve in water namely that they generally dissolve by decomposition ; in fact that when two liquid substances are in presence of one another as binary coinpomds they are present not only as such but at each moment also to some extent as the products resulting from tlie interchange of their particles ; so that sodic chloride for exnlzple when dissolved in water does to some extent consist of the products formed by the interchange of sodium and hydrogen that is to say of hydric chloride aiid sodic hydrate.The proportion between the two original compounds and the substances formed by their decomposition depends upon the relative velocities of the movemefits which decompose the original compounds aiid of the movements which reproduce them. These things from their very nature are extremely difficult to prove; they are processes of rayitl motion or iiitercli;~iig~ and the substaces in question cannot be fixed in any particular state except by removing them from the sphere of decomposi- SOLUTION OF GASES IN WATER.tion. If by any such interchange an insoluble compound would be formed we know that it is actually formed because if a sinall quantity of silver chloride for example is produced it imnie-diately goes down and is removed from the circle of decomposi- tion so that the reproducing change between it and the cor-relative compound takes plnce much more slowly perhaps indeed at a rate incomparably slower than that with which the decom- posing change has taken place. Dr. Muller’s case is one which bears in a very direct and important manner on the general proposition and his introduction of ultramarine as a test for the discovery of free hydrochloric acid seems to affortl a strong confirmation of tho views above detailed.The ultraniarine is decomposed by hydric chloride but not by sodic chloride and therefore its decomposition in the case above alluded to seems to furnish very good evidence that hydric chloride is present in the liquid. It is hardly likely that so weak an acid-salt as hydric carbonate could expel hydric chloride except in iiifini- tesimally small quantities but if soda is present in any way in the liquid the carbonic acid added to it will combine with it and diminish the rapidity with which the reverse changes take place. The other reaction of the carbonic acid and chloride of lead is also an exceedingly interesting observation on the same kind of reaction.Dr. Hugo Niiller observed that in the last mentioned ex- periment it is much easier than in the former case to ascertain whether the action has really taken place because the solution can he warmed and some of the liberated acid distilled over ; besides the reaction is completed more quickly. It might be imagined that by heating the mixture of chloro-carbonate and carbonic water the stutus quo would be gradually reproduced ; but this is not the case; a certain amount of the origiual com- pounds is indeed reproduced ; nevertheless a certain quantity of hydrochloric acid cau be actually distilled over. and of course a proportional quantity of lead carbonate will remain as ultimate residue. The President in further illustration of the principles above considered referred to some experiments which he made about twenty-five years ago 0x1 the action of chlorine on water in presence of shlts like sodic sulphate.Chlorine in coutact with water forms hydrochloric and hypochlorous acids C1 + HHO = HC1 + IIClO as is shown by the fact that on adding silver ABEL Or\’ EXPLOSIVE AGESTP. nitrltte to the solution half the chlorine is precipitated as silver chlorides while the liquid retains its bleaching power uiidi-minished. Moreover aqueous chlorine decomposes sodic sulphate and other neutral salts even calcic carbonate and otlier similar compounds. He remembered making a considerable quantity of hypochlorous acid by leaviLig aqueous chlorine in contact with sodic sulphate the reaction most probably consist- ing in this that the sodic sulphate in presence of water waB partly coiiverted into hydric sulphate and sodic hydrate which latter reacted with the chlorine so as to form sodic chloride and hppochlorous acid. There is no doubt that these actions of masses are not sufficiently attended to.