sels formed from these membranes when they are filled with solutions of various solids and immersed in pure water, depend on the nature of the substances in solution, and may be used for determining the concentrations of the solutions. And, further, that just as we can deduce the relative weights of the molecules of gases from measurements of the relative densities of these gases made at known temperatures and pressures, so we can deduce the molecular weights of many substances in dilute solutions, if we measure the concentrations of these solutions, their temperatures, and their osmotic pressures. Or, to put the matter in another way, that in many cases the quantities of substances which exert equal osmotic pressures correspond to their relative molecular weights. Measurements of osmotic pressure have not, it is true, supplanted the earlier methods of weighing molecules; but the above facts and the circumstance that osmotic pressures vary with changes of temperature in a manner which corresponds with the behavior of gases forces us to ask ourselves the question, May we not transfer to the molecules in dilute solutions what we know about the molecules of gases? If so, must we not suppose that the former, like the latter, are free and without attraction for one another? Must we not, that is to say, regard a dilute solution as a mere homogeneous mixture of its constituents comparable with such a mixture as atmospheric air? How are we to reconcile such an hypothesis as this with the facts of a different order which may be brought to the support of the hydration theory?

We must now turn to another side of our subject. As long ago as the year 1857 Clausius, the founder of the kinetic theory, suggested an explanation of electrolysis which assumed first that every electrolyte consists of two parts, identical, in the case of salts, with the

metallic and acid radicles whose exchanges can be traced in chemical reactions. Secondly, that when a saltsay common salt or sodium chlorideis dissolved in water, the atoms of chlorine and the atoms of sodium which make up the molecules of the salt do not remain permanently coupled, but change partners from time to time, and occasionally even lose their partners as the result of encounters between the molecules, and thereafter wander alone in the solution until they collide with atoms of the opposite kind, when they may again combine and reconstitute molecules of sodium chloride. And, thirdly, that when a compound is decomposed under the influence of an electric current, the free atoms, ог "ions," alluded to above, form the vehicle by which electricity is carried between the electrodes. On this view of the nature of electrolytes an aqueous solution of sodium chloride would contain, at any moment, not only many molecules of the original salt, but also a certain number of free ions. These latter would go to the two electrodes in the process of electrolysis, and fresh supplies would constantly be produced by the continuous dissociation of further portions of the salt, until the whole had been resolved into its constituents.

We have seen that in 1887 the great Dutch chemist, van 't Hoff, pointed out that if we prepare dilute solutions of two substances A and B, whose molecular weights are already known, making these solutions of such concentrations that equal volumes-say one pint of each-contain equal numbers of molecules, and compare their osmotic pressures, then we shall find these pressures are equal. There are, however, some notable exceptions to this rule, and it is found that when a solution, such as a solution of common salt, which conducts electricity is compared with a solution which does not conduct

electricity, the osmotic pressure of the former is considerably greater than that of the latter. Now we might explain this fact by supposing that van 't Hoff was wrong, or we might explain it by supposing that mistakes have been made in determining the molecular weights of the substances used in our experiments. But there is at least one other reasonable alternative. Suppose that the Clausius theory of electrolysis is true, suppose that the molecules of electrolytes in solutions are partly broken up into ions, and not only to a slight extent, as Clausius imagined, but to a considerably greater extent than he suggested. Then there

would be more separate particles present in the given volume of the conducting solution than in the equal volume of the non-conducting solution, and the actual osmotic pressure of the former would be greater than its calculated osmotic pressure. For the dissociation of the molecules of the salt into their ions, by increasing the number of particles present in any given volume of the solution, would raise the value of all those of its properties which, like osmotic pressure, depend upon the number of particles present in unit volume of the solution. If we accept this solution of the problem, and it is supported by other qualities exhibited by solutions of electrolytes, then it would seem that the abnormal osmotic pressures of substances of this class are not the result of error, but, on the contrary, vindicate the electrolytic dissociation hypothesis, and afford us a means of measuring the extent to which dissociation has taken place in any given solution.

But beautiful and attractive as these last speculations may seem, we must not forget that, after all, the conditions of the molecules of a solute, as they wander for the most part in solitude and far apart from each other amid relatively dense swarms of the mole

cules of the solvent water, may not be strictly comparable with the conditions of the molecules in a gas which are not thus hampered by closely packed crowds of attendant alien particles. I ought, therefore, to add that some of the ablest of those who have studied solutions are disposed to hold that the chemical theory may yet be so extended as to bring it into harmony with the above and other facts which at present stand in the way of its acceptance; while others, still fascinated by the physical aspects of the problem, are disposed to transfer their attention from the solute to the solvent, and suspect that "the active rôle in aqueous solutions" is played not by the substance dissolved, but by the molecules of the water in which it is dissolved.

"An ideally perfect solution," said the President of Section B, at the last meeting of the British Association, "that is, a solution the physical properties of which are determined solely by the number of molecules it contains in a given volume, must consist of a solvent and a solute which have no chemical affinity for each other, so that their molecules will neither associate nor dissociate in solution."

If we could accept this view of the matter the problem would become relatively simple, and its solution might be near at hand. For we should then be justified in confining our attention to a few of the less complex cases, which, it must be admitted, is pretty much what has been done in this present article. But the whole truth about solutions will hardy be reached by following this single road. When we study phenomena connected with solutions, whether it be the liquefaction of a solid like sugar or salt in water or some other familiar liquid, the dissolving of a solid metal in a melted metal, the dissolving of a natural silicate in a molten rock, or reversals of these processes such as occur in the crystallizing

of salts from their solutions, of metals or metallic complexes from molten alloys, or of the naturally occurring minerals from rock-magmas in prehistoric times, we are required, as two great modern workers in this field have remarked, to read a true palimpsest. In every case Nature has inscribed, as it were, two stories on a single parchment. There is the physical inscripThe Cornhill Magazine.

tion, there is the chemical inscription, closely written, one upon the other, line upon line, in every direction all over the parchment. We may seek to decipher one or we may seek to decipher the other, but neither by itself will yield the whole truth. If we want that, sooner or later we must read them both.

W. A. Shenstone.

The interest which the pubic increasingly takes in the conditions of life in the East End of London encourages me to write a short account of a visit I lately paid, in the character of temporary help, or "stop-gap," to a ladies' settlement.

The slum in which it was situated can without exaggeration be described as uncivilized and Hooligan to a greater extent than any other in the London area; my experience, therefore, may not be without interest to those who are ignorant as to the manner in which half the population of our great city exists. To myself it was a revelation: unlike anything I had imagined possible and if others can be induced to give their services for three or four weeks occasionally as I did, my story will not have been written in vain.

I went to help as well as I could the overworked ladies of the settlement, in the absence of some of their colleagues who had gone away for a short rest. The Christmas holidays were in full swing, with the usual treats for girls and boys and men and women of the slum, and during my visit of three weeks I assisted at nine treats, besides the daily routine of district visiting at the houses of the residents, visits to the factories, and superintendence and entertainment of clubs, which never

hour's breathing

ceased. Half an space for any one of the ladies occurred but rarely.

A book written by a hard-working East End clergyman which some time ago attracted a good deal of attention, and which I have myself read, appears to me to do scant justice to ladies' settlements. It describes them as up-todate nunneries, owning no allegiance beyond their four walls, and with a head lady as parish priestess. Whether this be true of other settlements it might be presumptuous in me to say, though it does not at all tally with what I have heard from persons presumably much better informed than myself. But it certainly is not a true description of the particular settlement of which I have personal knowledge. I cannot imagine anything less resembling a nunnery. A head, of course, there is, and must be if the varied and laborious work of the ladies is to be conducted systematically; and unless so conducted it could not be successful. But all ladies' settlements in the East End work under the Bishop of London or the Bishop of Stepney, and under the clergy of the several parishes in which they are established. And they are not sisterhoods. The ladies can come and go as suits their convenience. Both resident ladies and visitors (work

ing visitors, be it observed, and none other are received) regard the settlement as a home and centre for work, either permanent or temporary as may suit their inclinations. The settlement which I visited could accommodate seven or eight resident ladies, each with a separate bedroom. Visitors are expected to pay a certain amount weekly for their board and lodging. Resident ladies pay rather less. Three good servants were kept in our house, and perhaps a short description of the building and its surroundings may here not be out of place.

Blank walls and factory chimneys, narrow, dirty, mean streets, and more blank walls-that was the depressing vision which met my eye as I drove towards the settlement, and I confess my heart sank very low indeed when the cab drew up, in the meanest street of all, at the door of the house I was to consider a home for three weeks. Once inside, however, the kind welcome and cheerful faces of the three resident ladies in charge dispelled my gloomy forebodings. With great pride they showed me first the large, airy club-room, opening out of the entrance hall. I was struck with the size of the fireplace and the number of windows, and last, but not least, with the fact that a full-sized grand piano stood invitingly at one end of the long room. Observing my surprise, the head lady explained that in a few hours I should be asked to play for the club girls, who were expected that very evening both for needlework and dancing; and it occurred to me that the large fireplace and numerous windows might have some relation to the requirements of ventilation-an inference amply verified before the end of the evening. She then showed me the excellent kitchen and sculleries, and lastly, with some apologies for its size, the dining-room. It was cosy, and that was all I could say; but no doubt some day a better

room will be provided. Upstairs I was taken to see a beautiful little chapel used for morning and evening prayers, and sometimes for other services when the bishop or clergy come on special occasions. This, I was informed, was kept clean and in order entirely by the ladies. Next I was taken to my own bedroom, which was on the same floor, as were also the rest of the bedrooms and a good bathroom. It was all cheerful and well furnished. But the drawing-room, as they explained, was the place to which all went as a peaceful haven whenever there was a spare half-hour for any one to rest. A large room with three or four sofas and as many armchairs, four or five writing-tables, books, pictures, flowers, everything to please the eye and the mind. It was a room calculated to make us feel at home. So much, then, for the interior arrangements. Outside was a strip of gravel and a border (which in summer I was told was gay with flowers), called by courtesy the garden. High walls screened it from the noisy streets outside, and in the summer months it is used as a playground for the eighty or one hundred children belonging to the boys' and girls' clubs, who play for hours together, superintended by the residents and visitors, who take the duty in turn.

Of the first importance in a slum settlement is a large cheerful club-room both for girls and for boys, and perhaps more particularly for girls. In the slum in which I was working these were all, or nearly all, factory hands. I believe the great temptation to which factory girls, as a class, give way is the temptation to drink. Certainly it was so in this particular slum, where they had succumbed to it before the ladies' settlement was established, and where they still habitually frequent the numberless public-houses in the place; spirit clubs, too, exist in every factory,

and to these the girls pay most of their savings week by week for the express purpose of providing an occasional debauch, or, as they would themselves call it, "bust up."

In the slum I am speaking of intemperance is the fashion. Not to get drunk occasionally is to be out of the fashion. And though hard-working clergy and the not less devoted ladies of the settlement working under them labor to stamp out the awful habit, the results they can show for the toil of years are lamentably small. Yet, discouraging as this sounds, a nucleus has been formed of factory girls, rough and excitable and rowdy enough in all conscience, who, in the midst of well-nigh insurmountable difficulties, aspire to a better and higher life than it seemed likely they should have any chance of living when they were first launched upon the world. Belonging to the settlement club brings a girl or boy into frequent contact with ladies of culture and refined manners. And from the entertainments which they take part in of an evening at the club they at any rate learn that there are pleasures superior to dram-drinking. Even the tiny ones are enrolled in the girls' and boys' clubs and trained to become members of the Band of Hope. Perhaps it is not too much to hope for that the next generation of factory girls will be an improvement upon the existing ones, thanks to those, whether clergy or lay helpers, whose lives are devoted so nobly to bring it about. Now I will briefly describe my first evening in the club, typical as it was of many others.

About 7 P.M. some five-and-thirty girls bounced into the room, and greeting the two resident ladies and myself with rough good humor, as if we were all pals together, at once seated themselves, with much noise and chaff, at three deal tables on which were arrayed various garments, more or less unfinished, intended eventually to

clothe a child belonging to the Waifs and Strays Society, in whom the factory hands had been encouraged to take an interest.

Feeling a little nervous at their rough-and-ready method of making making themselves at home, and unaccustomed to the utter absence of shyness and decorum which they displayed, I seated myself at the piano in some trepidation, at the request of the head lady, who then explained to the company that I had just arrived to help for a short time at the settlement. She added that instead of listening to

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story-book as usual while they worked they as a special favor would be given the opportunity to listen to any music I chose to play, and this, to my relief, was extremely well received. "Go on, Miss, we ain't pertickler, but give us something cheerful to start with," said one big, bold-faced young woman near me, and a loud stamping of feet emphasized her request. cordingly I dashed into a cheerful, rousing march, and was accompanied throughout by stamping and occasional singing. This demonstration was gently but firmly suppressed by the head lady, whose tact was unfailing, and whose sympathy with the girls and knowledge of the excitable spirits she had to manage was quite admirable. Gradually I played more sentimental music, and at last ventured to give them a favorite Bourrée by Handel. Greatly to my relief, this was applauded, the marked time and rhythm exciting renewed stamping and thumping on the tables. As eight o'clock struck, amid a great noise and excitement, tables were shoved aside and I was requested by the head lady to glance at a dance programme she had written out and pinned on the wall, and to play polkas, waltzes, jigs, and lancers in succession for an hour or longer.

There was so much noise and laugh