originally present, when the amount of anilide and chlorine in the system in equilibrium is very small, as in the case in media below 50 per cent acetic acid. [HC1] is constant. Hence

dichloroanilide]/dt=k11.Const. [chloroamine]/K=k' [chloroamine], a reaction of the first order.

But it still remains to suggest causes for the extraordinary reactivity of anilides towards substituting agents and their rigid adherence to the ortho-para law. The hypothesis may be put forward that the constitution of anilines and anilides, similar to but in a less degree than p-nitrosophenol, permits of the passage into a dynamic isomeride of quinonoid structure, which is accompanied by the wandering of hydrogen of the imino group to the o- or p-position. It is this isomeride which is reactive. The almost exclusive occurrence of o- and p-quinonoid compounds accounts for the position taken up by the substituting group. Just as with the hypothetical intermediary complex, a change of structure of the benzene nucleus is assumed; but here the mobile hydrogen atom and not chlorine migrates.

Further, this suggestion brings out the close analogy of the anilines and anilides with the phenols, where there is little evidence for the formation of compounds of the substituting agent with the oxygen, and much other evidence for the occurrence of a quinonoid structure.

This suggestion, on the other hand, relegates to the background the attractive view of the part played by the latent valency of the tervalent nitrogen, which permits of a ready means of primary union between the substituting agent and the anilide.

Flürscheim (Journ. Prakt. Chem., 1905, [2], lxxi., 497; 1907, [2], lxxvi., 165) has attempted to account for the laws of substitution in aromatic compounds by reference to latent or rather partial valencies of certain of the carbon atoms in a monosubstituted derivative of benzene; with certain substituents the attractions on the hydrogen atoms in the o- and -positions, and with others in the m-position are loosened, and hence more readily re-substituted. It is obvious that this view is independent of intermediate compounds, and would harmonise generally with the facts of chlorination as recorded in the foregoing.

Recently Lowry has discussed this subject (Science Progress, 1959, iii., 616; iv., 213), and has suggested various ways in which the facts may be accounted for. He points out that the migrating group is always present in the system, whenever isomeric change is taking place.

II.-Bromination of Anilides and the Conversion of
Bromoamines.

(With W. J. JONES, B.Sc.). The interaction between bromoamines and hydrobromic acid only differs in degree from that between chloroamines and hydrochloric acid. Tintometric measurements have shown that in acetic acid of all dilutions the reaction is quantitatively:

Ar.NBrAc+ HBr Ar.NHAC + Br2. The direct bromination of the anilide is therefore always identical with the conversion of a bromoamine under the influence of hydrobromic acid.

The bromination which results when a chloroamine is treated with hydrogen bromide (or a bromoamine with hydrogen chloride) is a far more rapid process. In both these cases bromine chloride is formed and is the brominating agent.

Bromination, however, differs in one respect very markedly from chlorination in that hydrobromic acid and bromide exert a powerful retarding influence. Thus in the presence of four molecular proportions of hydrobromic acid, bromine does not act on acetanilide in glacial acetic acid at 16°. Hydrochloric acid, even when present at 8-10 times the concentration of the chlorine, has a scarcely perceptible effect.

The bromide exerts its maximum effect in glacial acetic ❘

acid. Addition of water reduces the effect, and as Fries has shown (Annalen, 1906, cccxlvi., 128), dilute acetic acid is the best medium for bromination of anilides. Thus in one of our experiments, in 75 per cent acetic acid, using the molecular ratio, 8H Br: Br2: C6H5.NHAC, threequarters of the acetanilide was brominated in twenty minutes. p-Chloroacetanilide in glacial acetic acid is brominated too slowly for easy measurement; in 50 per cent acetic acid, k1=0.36, and in water = 12.

The cause of this influence lies in the union of the bromine with bromidion forming Br'3. We have shown by the method of aspiration that in glacial acetic acid, when bromine and hydrobromic acid are in molecular proportions, 75 per cent of the bromine is combined with bromidion, but as the acetic acid is diluted the percentage of free bromine rapidly increases. In water we obtained by our method for the equilibrium, K = [Br2] [Br'] [Br'3], values similar to those found by Jakowkin (by measurement of the distribution ratio between water and carbon tetrachloride) (Zeit. Phys. Chem., 1896, xx., 38): our value for K is o'62, and Jakowkin's K°=0·63.

While no new finds

AT the Adelaide meeting of the Association, in 1907, I had the honour to present a paper embodying all the then available information with regard to the occurrence of tantalum and niobium in Australia. of minerals containing these metals in the Eastern States have come under my notice in the meantime, a considerable amount of further information has been collected with regard to West Australian occurrences, which it is the object of this paper to describe.

Until quite recently it was a matter of impossibility to separate occasional fragments of black tantalates and niobates from parcels of black stream tin except where they showed well-developed crystal faces or other prominent characteristics. The publication, in Vol. viii., of the Journal of the Chemical, Metallurgical, and Mining Society of South Africa, of Prof. G. H. Stanley's "New Test for Cassiterite," has very materially altered the aspect of affairs. This method is invariably used by the author in his examination of tin ores for rare minerals. A shallow dish about 4 inches by 3 inches is made by turning up the edges of a piece of stout sheet-zinc; in this are placed the concentrates in the form of sand or coarse fragments up to

inch diameter, and then covered with dilute (5E) hydro

chloric acid. In about one or two minutes the acid is

poured off and replaced with water, when all fragments of cassiterite which have been in contact with the zinc are found to be coated with a bright deposit of metallic tin, so that they can easily be picked out, leaving a residue of other minerals which are not appreciably affected by the short immersion in dilute acid. This residue is submitted a second time to the same process, as possibly it may contain some fragments of cassiterite which are not coated because they have not been in contact with the zinc. After drying the final residue, it is freed from magnetite with a hand magnet, and if necessary from ilmenite by a weak electro-magnet. Hand-picking will remove quartz, monazite, &c. The final residues are then examined by chemical and physical tests for the tantalum minerals, tantalite, euxenite, &c.

If the method here outlined were applied to all samples of tin concentrates in the possession of members of the Association, it is possible that our knowledge of the dis

tribution of tantalum and niobium in Australia would be

greatly extended.

* A Paper read before the Australasian Association for the Advancement of Science, 1909.

which were quartz, three magnetite, and one monazite. The remaining 24 appeared to include both euxenite and fergusonite.

A parcel of alluvial monazite concentrates from Cooglegong contained small proportions of cassiterite, euxenite, columbite, and probably fergusonite.

Another sample of alluvial tin ore from the Shaw Tinfield near Cooglegong was also examined. It was somewhat fine grained, 70 per cent passing a 10-mesh sieve. Twenty-five grms. of the coarser particles were tested, and yielded 93 per cent cassiterite. Most of the balance was monazite, but a few small crystals of tantalite were present.

Wodgina. In my previous paper mention was made of the occurrence of microlite in this district, and as this mineral had not previously been recorded in Australia_an incomplete analysis of it was submitted to you. The analysis has since been completed, the final results being

in a matrix of granular albite, the latter with a little quartz and muscovite forming about 72 per cent of the ore. The remaining 28 per cent consists of a tantalate with a somewhat resinous lustre, and varying in colour from pale cinnamon-brown to dark brown. It occurs in indistinct crystalline aggregates, the system of which has not been determined. In thin slices it is sub-transparent, and apparently homogeneous except for gradual slight variations in the depth of colour, which apparently deepens under alteration along cleavages, &c. Carefully selected material was analysed with the results given above.

If the tin is present in combination this yields a formula 3MnO.3 Ta205.SnO2. In the large proportion of tin oxide and in the light brown colour of the powder it resembles ixiolite of Nordenskiold (Kassiterotantal of Hausmann), until however, its crystallographic system has been determined, and its apparent uniformity in tir. contents confirmed, its exact species must remain in doubt. The typical mangano-tantalite of Wodgina differs from it in several respects, viz. :

1. It contains far less tin oxide (0.5 per cent as against 8.9).

2. It is not quite so hard (6'5 as against 7.0).

3. It is quite opaque even in very fine powder.
4. Its colour is black and streak brownish black.
5. Its lustre is very different.

It resembles, on the other hand, this mineral somewhat closely in

1. Specific gravity (7.4 and 7.1).

2. Ratio of basic protoxides to acidic pentoxides being

one to one.

3. Chief base being manganese, chief acid tantalic. 4. Absence of rare earths from both.

Greenbushes.-Up to the time of the writing of my previous paper no traces of crystalline form had been observed on any of the Greenbushes tantalite. I have since seen a water-worn fragment of 25 grms. in weight which exhibits a radiated structure similar to that seen in some of the Moolyella ore.

A number of stream tin ores from Greenbushes have been examined for tantalite and stibio-tantalite with negative results. It would appear as if these minerals were confined to a small portion only of the field. Tantalum has, however, been detected in clean cassiterite from this field. A clean crystal from a lode on the South Cornwall Mine was found to yield the results given below, whilst a rolled pebble from North Greenbushes yielded 1.15 per cent Ta205.

Cassiterite, Greenbushes.

15'9 2.8

Per cent.

Molecules.

Tantalum pentoxide

70'49 7.63

Magnesia.

Ignition loss

Another interesting mineral has recently been received from the Wodgina district. It occurs in a very fresh state

Bellinger. This is a new locality for tantalates, situated close to the South Coast. The rock formation is granite traversed by veins of pegmatite, one of which, twelve miles west of Point Malcolm, gave promise of yielding muscovite of commercial quality. A mineral lease, 112H, was taken up on this vein during 1907 in order to open up the mica, and in the course of operations small quantities of a black mineral were met with, which was thought to be tin ore. Examination proved it to be tantalate and niobate of iron and manganese varying from ferro-tantalite to mangano-columbite in composition. The specific gravities recorded were 5'59, 6·60, 7·10, 7'60, indicating percentages of tantalic oxide from 15 up to 75. Most of the mineral was in irregular broken fragments, but a few imperfect tabular crystals were noticed in which the faces "a" and "b were prominently developed, whilst traces of "u" were also seen,

INCLUDING PAINTS AND PAINT MATERIALS, INKS, LUBRICATING OILS, SOAPS, &c.

By PERCY H WALKER. (Continued from p. 206).

Phenolic Disinfectant. THE phenolic soap mixtures can generally be identified as they form an emulsion with water. They consist of phenolic soaps and hydrocarbon oils and are quite variable in composition. The following scheme for analysis is only a slight modification of that given by Allen (Commercial Organic Analysis," 3rd edition, ii., [2], 262). The only important modification consists in the recovery of light hydrocarbons, which by Allen's process would be lost.

1. Volatile Hydrocarbons.-Mix the sample thoroughly, weigh a portion of somewhat more than 100 grms. in an Erlenmeyer flask with a funnel. Pour about 100 grms. into a distilling flask of 150 to 200 cc. capacity, using the funnel to prevent the disinfectant from getting on the neck of the flask, weigh back the Erlenmeyer flask and the funnel, and get the exact weight by difference. The delivery tube of the distilling flask should be bent so that it can connect with a small vertical condenser; all connections are of cork. Heat the flask in a paraffin bath, slowly and carefully, not exceeding 130° C., for one and one-half hours, or until the substance becomes solid or ceases to give off volatile matter. The receiver is a small separatory funnel with a short tube, the tube of the condenser being connected with it by a cork having a groove cut into it for the free passage of air. The funnel is weighed empty, and again with the total volatile liquid; then the water is drawn off and the remaining liquid weighed as volatile hydrocarbon.

2. Pyridine.-Dissolve the residue in the distilling flask in water, it is usually necessary to add 60 cc. of water; heat slowly to avoid foaming and leave the flask in the steam-bath for about an hour. Wash the soapy solution into a 500 cc. separatory funnel, add dilute sulphuric acid (1:3) until the liqiud is distinctly acid to litmus, cool, shake with ether, drain off the acid layer and shake it twice with additional portions of ether, wash the ether twice with water, unite the acid water solutions, transfer to a large round-bottomed flask, and render distinctly alkaline with sodium hydroxide, but avoid a great excess of alkali, as it will cause foaming. Use a spray trap and a large condenser. In all distillations tie the stopper in the flasks and condensers, as they are liable to be blown out, and distil in a current of steam until all of the pyridine has passed over. This is usually a tedious operation, but in most cases the pyridine can be driven over in the first 600 or 700 cc. To ascertain whether all of the pyridine has come over, mix 10 cc. of the distillate with 10 cc. of a solution of one drop of half-normal sulphuric acid in 50 cc. of water coloured with methyl-orange. Tbe 10 cc. of distillate should not change the colour of the solution. Transfer the distillate to a 1000 cc. graduated flask, add an excess of half-normal sulphuric acid, fill to the mark, mix, and titrate aliquots back with fifth-normal sodium hydroxide using methyl-orange. From the amount of half-normal sulphuric acid neutralised, calculate the percentage of pyridine (1 cc. of half-normal sulphuric acid corresponds to o'0395 grain of pyridine).

3. Heavy Hydrocarbons.-The ethereal layer above the acid solution in which the pyridine is, contains hydrocarbons, phenols, and fatty and resin acids. Add a 25 per cent solution of sodium hydroxide in amount sufficient to combine with all the fatty and resin acids and phenols, shake, add water to dissolve the soaps, shake again and allow to settle. It will frequently be observed that there are not two layers, but three, and care must be taken to

Bulletin No. 109, Revised, U.S. Department of Agriculture, Bureau of Chemistry.

mediate dark alkaline layer below it. Draw off the liquid underneath the ether, shake out twice again with ether, wash all ether portions three times with water, unite the ether solutions in a weighed Erlenmeyer flask, distil off the ether, dry for three-quarters of an hour on a steambath, wipe out the moisture from the neck of the flask, and weigh as heavy hydrocarbons. Concordant results cannot be obtained by drying to constant weight, hence it is always much better to leave the Erlenmeyer flask on the steambath exactly three-quarters of an hour after distilling off

the ether.

4. Phenols. Heat the alkaline liquid separated from the heavy hydrocarbons on the steam-bath to drive off the ether, transfer it to a round-bottomed flask, make distinctly acid with sulphuric acid (1:3) and distil in a current of steam until no more oily drops pass over (do not use a spray trap); to the distillate add an excess of sodium hydroxide, evaporate to about 20 cc., transfer to a narrow graduated stoppered cylinder, acidify with sulphuric acid (1 : 3) keeping it cool, mix, allow to settle over night, and measure the layer of phenol. The volume in cubic centimetres multiplied by 105 gives the number of grms. of phenols.

5. Fatty and Resin Acids.-Cool the residue in a distilling flask, extract with ether, distil off the ether, dry on a steam-bath three-quarters of an hour, cool, and weigh as fatty and resin acids.

6. Other Tests.-Ash a 10 grm. portion of the disinfectant and determine the alkalinity of the ash, and whether the alkali is soda or potash. In determining the relative values of disinfectants of this class, the sample should be submitted to a bacteriological test. In the absence of such a test the substance may be graded by the sum of the percentage of phenols and pyridine. This is, of course, only a general approximation, as the hydrocarbons and soaps doubtless have some germicidal action.

Pipe Covering and Cement.

1. Sampling.—The insulating covering for steam pipes is generally made of a hydrated basic carbonate of magnesium and serpentine asbestos. Such material is difficult to sample, but by cutting out pieces of about 1 grm. weight from twelve or more different places on the section of pipe covering, grinding in a mortar and thoroughly mixing, a satisfactory sample can generally be obtained. Preserve this sample in a tightly stoppered bottle. The cement for pipe covering is of the same composition as the cover itself and is examined in the same way, but it is much easier to sample.

2. Moisture (Loss at 105° C.).—-Dry 1 grm. of the prepared sample for two hours at 105° C., weigh, and calculate loss in weight as moisture.

3. Loss on Ignition.—Ignite sample used for the moisture determination to constant weight. It is necessary to stir the material several times to insure heating all parts of the sample.

4. Asbestos.-Treat 5 grms. with 100 cc. of 6 per cent acetic acid, heating on the steam-bath to hasten solution. Filter on a Gooch crucible, wash, dry at 120° to 130° C., and weigh. This result is considered to represent asbestos. Then ignite to determine the water in the asbestos (about 14 per cent generally), which is deducted from the total, as it has already been included in the "Loss on Ignition." By this method all matter insoluble in acetic acid is assumed to be asbestos. If the presence of other insoluble material is suspected, filter on paper and examine the residue with the microscope or make an analysis of it. This, however, is seldom necessary. Serpentine asbestos is slightly soluble in acetic acid, but this error may be neglected.

5. Alumina and Iron Oxide.-Add ammonium chloride and ammonium hydroxide to the filtrate from the asbestos, filter, dissolve precipitate in hydrochloric acid, re-precipitate with ammonium hydroxide, filter, wash, ignite, and weigh as alumina and iron oxide.

6. Magnesia.-Unite the filtrates from the alumina and