permanganate of potash has little action, and it has not

VOL. XXVIII. No. 729.

MEMORANDUM ON THE PURIFICATION OF DRINKING-WATER,

WITH SPECIAL REFERENCE

If we divide the organic matter in water into three classes, viz. :—

(1). Matter already in a state of putrefaction,
(2). Matter ready to become putrid,

(3). Matter which is slow to decompose,

GOLD COAST.

By WILLIAM CROOKES, F.R.S., &c.

THE following memorandum has been drawn up at the request of Sir William Muir, of the Army Medical Department :

In the absence of any specific information as to the quality of water likely to be found on the Gold Coast, the following remarks are necessarily somewhat general in

character.

Disinfection of water cannot be effected by one substance which removes all the evils at once. There are likely to be many septic bodies in various conditions, and each has to be attacked in a special way.

The danger certainly lies in the organic matter present in the water; but it bears no constant relation to the quantity present. Water may contain a large quantity of peaty organic matter-as much as 4 or 5 grains to the gallon-and be harmless: whilst a very small fraction of this quantity of another kind of organic matter may make it a deadly poison.

Malaria appears to be caused by the decomposition of organised bodies. Soils generally are acid, and the drainage-waters from them are comparatively harmless. But, under conditions which are frequently likely to obtain in a tropical country, such as great heat, low lying position, damp marshy soil, exuberant and dense vegetation preventing excess of solar rays to the soilthe soil is likely to become more alkaline than the vegetation will bear; putrefactive decomposition will commence, the oxygen in solution in water will be insufficient to restore the balance, and malaria will be the result. In the drainage water from such a tract of country the germs of fatal diseases are almost certain to be present,-to what extent we are ignorant.

That the poison is in the water rather than in the air is well illustrated by a circumstance related by Dr. Woods (CHEMICAL NEWS, vi., 307). Two ships were dispatched simultaneously with troops from Algeria to France, both under similar circumstances, excepting that the supply of water had been drawn in one case from the low marshy lands where ague was prevalent, whilst the other ship had taken water from a locality situate at a greater elevation, and where the disease was unknown. The passengers on board the first transport were quickly seized with remittent fever, whereas no case of illness occurred on board the second vessel.

The means relied upon for destroying or neutralising the poison in bad water are, with the general public, addition of permanganate of potash, and filtration through

charcoal.

For general purposes these may be sufficient, but in cases of real difficulty they are likely to be most unsafe, if not positively harmful as leading to a fancied security. Permanganate of potash exerts extraordinary destructive powers on some kinds of organic matter. Thus the offensive gases of putrefaction are at once deodorised, and many kinds of organic matters, such as oxalic acid, sugar, &c., are almost instantly destroyed. With other substances, however, such as the scent of musk, urea (from urine), the strong smelling valerianic acid, lactic acid (from sour milk), and butyric acid (from rancid butter),

it will be found, practically, that the matter in class I will be the only organic matter which permanganate of It will destroy this at once, whereas to destroy organic matter of the second class with permanganate of potash will require from fifteen minutes to an hour; and to destroy matter of the third class will require from some hours to some days. Moreover, living matter has considerable resistance to the oxidising power will live for upwards of an hour in water tinted with it, of permanganate of potash; microscopic animalcules and living beings, visible to the naked eye, will live in a much stronger solution.

If a soldier, provided with permanganate of potash, after mixing a little with water waits only a few minutes before drinking it, he will certainly imbibe most of the organic matter of classes 2 and 3; whilst he would have to defer quenching his thirst for about half an hour before the matter of the second class would be destroyed, and for at least a day before matter of the third class would be attacked; and even then he would be by no means safe. Practically, however, if the soldier used the permanganate at all, he would not be likely to do more than wait for a few minutes.

But the probability is so great as almost to amount to a certainty that the septic matter of the water would reside in the organic matter of classes 2 and 3.

The specific disease-producing particles are doubtless organised germinal matter, or cells, possessing physiological individuality, capable of preserving their activity for a certain time when out of the water in the form of slime, or even dust, able to adhere to material objects, and to be carried from one place to another on the clothing or in currents of air.

To remove these bodies from water, permanganate would be inoperative within the time in which it would be allowed to act. Filtration through charcoal would at first sight appear to be a satisfactory safeguard; but it is not sufficient, for many reasons.

In the first place charcoal acts mechanically as a filter, and should therefore remove solid germs. But these cells are supposed to be so extremely small that it is doubtful whether they would be kept back by merely passing water rapidly through an ordinary filter, whilst if they were kept back they would accumulate only with their tremendous power for evil uninjured, on the upper side of the filter, ready at the first accident to act as the focus of a pestilence.

The

In the second place a charcoal filter acts as an oxidising purifier for the water which passes through it. oxygen condensed in its pores destroys organic matter somewhat as permanganate of potash does. To keep charcoal efficacious, however, as an oxidiser, it should be allowed to get dry nearly every day, and should be frequently cleaned. Even at its best it is not likely that it will oxidise organic matter more readily than will permanganate of potash, and hence matters of the second and third class-probably the most dangerous of all—are likely to pass through.

There is another purifying agent which has stood the test of long experience, and which possesses properties which are especially valuable in the present case. I allude to sulphate of alumina. When this salt is added to water containing organic matter of different classes, it passes by that which is so easily oxidised by permanganate of potash, but it attaches itself to organised animal matter-living germs-and converts them into an insoluble substance like leather. It is not quite certain whether this tanning operation destroys

If

(U2O2)F1

Under the name of A B C compound a mixture of sulphate of alumina, clay, and charcoal has been successfully used by the Native Guano Company for the purification of sewage. At their works I have repeatedly seen the sewage of such places as London, Paris, Hastings, and Leeds, converted in the course of a quarter of an hour from an offensive looking, vile smelling liquid, into water, bright, clear, inodorous, and tasteless, nonputrescible, and so free from injurious matter as to allow delicate fish to live and thrive in it.

With a little necessary modification I consider that a mixture capable of acting thus on town sewage is the most suitable for the purification of water for drinking purposes on the Gold Coast.

I would suggest that the charcoal be omitted, and its place supplied by a permanganate. The ordinary potash salt will do, but if procurable in time I have reasons for believing that permanganate of lime would answer the purpose better.

I have prepared a mixture of

I part of permanganate of lime,
10 parts sulphate of alumina,
30 parts fine clay,

and find that when I add this to London sewage in the proportion of 20 to 10,000, the purification is very satisfactory, and the settlement rapid. With foul ditch water a less quantity will do.

2(U2O2)F1+NH1Fl+xHO 4(U2O2)Fl+3Ba Fl+4HO 2(U2O2) Fl+3K FI

2(U2O2) FI+Na Fl+4HO 2(U2O2)FI+Na Fl+8HO

These all fluoresce with various degrees of brightness, and yield very remarkable spectra, having, in the case of two of the double salts especially, a strong similarity to the double oxychlorides in complexity of structure. Their absorption spectra are also marked.

Uranic Oxyfluoride, (U2O2)Fl.--This salt gives a spectrum which, in the general character of its bands, much resembles the acetate, normal sulphate, &c., or what may be called the normal type. There are, however, in it slight indications of inflections of brightness in the individual bands, which we find strongly developed in the double salts, These indications are, however, too delicate to be correctly represented in the cut, being, in fact, only recognisable when specially looked for. This spectrum The absorption spectrum of this is shown at 2 of Fig. 12. substance is likewise well marked, and is shown in 2 of Fig. 13. When dissolved in water, and acidulated with hydrofluoric acid, this yields an absorption spectrum such as is shown at 3 of Fig. 13. In this the general absorption is strong, and the bands are relatively faint. If no acid is added to the solution of the uranic oxyfluoride, we obtain a spectrum of absorption similar to the above, but with the bands all displaced a little upwards; thusAbsorption-Bands of Uranic Oxyfluoride in Solution.

I am not prepared to say what the price of this mixture would be, but it would probably not be many pence per hundred gallons of water.

PRELIMINARY INVESTIGATION OF THE FLUORESCENT AND ABSORPTIVE SPECTRA OF THE URANIUM SALTS.* By HENRY MORTON, Ph.D., and H. CARRINGTON BOLTON Ph.D, (Continued from p. 234).

Uranic Oxyfluorides.

THE chemical relations of these salts have been made the subject of a special investigation by one of us, and will be found fully discussed, but the following brief notes may be useful in this place :

Uranic oxyfluoride is obtained by dissolving the sesquioxide of uranium in hydrofluoric acid. If the three-fourths oxide be treated with this acid, uranous fluoride also orms as an insoluble green powder, which may be separated by filtration.

Potassio-uranic oxyfluoride, 2(U2O2F1)+3KH, is best prepared by adding potassio-fluoride to a solution of uranic nitrate, dissolving the lemon-yellow crystalline precipitate in warm water, and crystallising. The corresponding sodium salt, being very soluble, can be prepared in this manner; it is obtained with difficulty by evaporating a mixture of uranic nitrate and sodic fluoride in a desiccator. It has the constitution 2(U2O2F])+NaFI+8HO. The

The Double Oxyfluorides.

Of these the most brilliantly fluorescent is the potassium salt, and we will therefore describe it in detail, and the others by reference to it. This salt fluoresces pretty strongly, and yields a spectrum in which each band is composite, the stronger or brighter ones showing three elementary stripes, which are recognisable, but by no means so decidedly marked as those of the double oxychlorides. In Fig. 12, No. 1 will give some idea of this spectrum.

The other double fluorides of this class yield similar spectra, the positions of whose brightest parts are given below. The barium salt shows the same structure in its bands as the potassium one, but the others exhibit only single blended bands. The following table will give the positions of the brightest line in each group in the various spectra, these being named in their order of brightness:

Fluorescent Spectra of the Double Oxyfluorides.

UFI
Potassio-uranous fluoride, 2(UFI)+KFI
Sodio-uranous fluoride, 2(UFI)+Na

None of these show any fluorescence, but their absorption spectra are well worthy of note. That of the uranous

In my two papers on the chemical constitution of succinic, malic, tartaric, and citric acids, I have endeavoured to embrace, by one theory, that particular section of mono- and poly-basic water-salts which are descended from the o. fine-begotten polyatomic alcohols, and it is with the view of still more fully developing and substantiating that theory, that I have bethought myself of extending my speculative labours in a new direction;

and with a differen: choice of materials. A rich and plentiful supply of suitable materials has been found to spring from the action of bromine on the water-salts of succinic, malic, maleic, and pyro-citric acids, as also on their pure or chlorinated anhydrides. This searching and powerful reagent is understood to vary greatly in its effects, according as it is administered in the dry state or in the presence of water; but, considering the vast magnitude of my subject, an exhaustive article on which would far exceed the limits of this paper, I have deemed it advisable to confine my remarks to the action of bromine on the aforesaid water-salts only, and while it is applied in a watery solution.

I may now state, by way of introduction, that my interpretation of this order of chemical phenomena is founded on the hypothesis that there exist three different modes or methods, according to which bromine in solution is capable of manifesting its chemical affinities. By the first of these methods, 2 molecules of bromine are supposed to unite directly with 2 mols. of water, with production of 2 mols. of bromo-peroxide of hydrogen, 2H2Br2O2, the oxygen of which is thus rendered more easily available for oxidising purposes, while the 2 mols. of hydrobromic acid are set at liberty or otherwise disposed of. By the second method, 2 mols. of bromine are supposed to combine directly with a given simple or complex carbon adjunct, and precisely in the same manner as 2 hydrogen molecules are wont to do, with this difference, however, that in the former case the recipient must always be a pure carbon adjunct, while in the latter case it may also be a hydrocarbon adjunct. By the third method, one of the 2 conspiring mols. of bromine is supposed to appropriate a molecule of hydrogen from a given simple or complex hydrocarbon adjunct, with formation of a molecule of hydrobromic acid, while the other molecule of bromine is made to step into its place.

2C2; H2Br2 2C2; H2Br2: 2C2O3 ~ 2C2O3. Both these compounds are engendered by the first method, consequently the accompanying molecular changes will consist, for the first compound, in the oxidation of the formous acid ally, at the expense of the newly-formed bromo-peroxide of hydrogen, and transposition of one of the hydrobromic acid molecules with the formylic alcohol principal, while the other is set at liberty; and, for the second compound, in the oxidation of the formous acid principal, and transposition of one of the hydrobromic acid molecules with the formylic alcohol ally, while the other is set at liberty.

When the ordinary malate is treated with bromine, the resulting substitution product is the bromo-malate

2C2; H2Br2 2C2; H2O2: 2C2O3 ~2C2O3,

where the same explanation holds good. This view of the molecular structure of the aforesaid brominated derivatives is also fully borne out by experiment. Thus, when a solution of the bromo-succinate is heated with oxide of silver, the bromide of that metal is precipitated, and the solution is found to hold the ordinary malate, clearly showing that the metamorphosis is accomplished by the newly-formed hydrate of silver transposing with the formyl-bromide principal. Similarly, when a salt of the dibromo-succinate is boiled with water or excess of base, the bromide of the metal is formed, in some cases with elimination of both bromine molecules, in others of one only. For instance, the soda-salt is, under this treatment observed to resolve itself into I mol. of sodium bromide and I mol. of bromo-malate of soda; whereas the silver-salt deposits 2 molecules of bromide of silver, while the inactive modification of the tartrate of water remains in solution. The baryta-salt, on the other hand, is found to differ from the two former salts in this respect, that by the loss of 2 mols. of water the previously-formed bromo-malate of baryta becomes converted into the bromomaléate of baryta

Baz03. H2O2.

a) 2(C2: C2); H2Bг2: 2C2O3 ~ 2C2O3,

whence the bromo-maléate of water may be easily obtained B) 2C4; with the aid of sulphate of water. The same compound may also be procured by heating the bibromo-succinate, a molecule of hydrobromic acid being expelled at the

same time.

H2O2. H2O2. a) 2(C2: C2); H2O2 : 2C2O3 ~ 2C2O3, B) 2C4;