of soda, and the mass having been boiled with water, the palladium was collected on a filter and ignited. It was purely metallic, and weighed 16.653 grains, being 51.97 per cent. of the dry, or 43.75 per cent. of the hydrated salt.

The liquor filtered from the metallic palladium was acidulated by muriatic acid, and precipitated by nitrate of barytes. It gave 37.492 grains of sulphate of barytes, containing 12.997 grains of sulphuric acid, equivalent to 40 17 per cent. of the dry, and to 33.82 per cent. of the hydrated salt.

These results give therefore for the

When the dried sulphate of palladium is exposed to the air, it rapidly re-acquires water to the extent of one equivalent, without becoming sensibly damp. This quantity was determined several times; the proportion being that 100 parts of the dry salt regained nine to ten parts of water, forming therewith a greenish olive powder. If the air be very damp, it subsequently deliquesces completely. By this property the sulphate of palladium appears to ally itself with the sulphates of copper, magnesia, &c.; but it differs widely from them in others. Thus, it is decomposed by water, and I could not succeed in forming any double salts by bringing it into contact with the alkaline sulphates. Its analogue here would appear to be the sulphate of mercury.

Basic Sulphate of Palladium.

When a strong solution of sulphate of palladium is mixed with much water it is decomposed; a deep brown powder is separated, and the liquid becomes very acid. By the addition of free sulphuric acid this action of water may be prevented; but on neutralizing this excess of acid by an alkali, even ammonia, a brown powder separates, which is found on analysis to be identical with the former.

The following analyses were made of specimens of this salt, prepared under various circumstances.

A. Prepared by dilution with water.

39.467 grains were heated over a spirit lamp cautiously until all water had been given off. The dry mass, which had become much darker in colour, weighed 35.994 grains, or 91.2 per cent., having lost 8.80 of water.

The dry powder was fused with carbonate of soda, and the metallic palladium collected precisely as described in the preceding article. It weighed 29.215 grains, or 73.68 per cent.

By the addition of nitrate of barytes the sulphuric acid was determined; it amounted to 2'408 grains, or 6'11 per cent.

B. Prepared by the addition of potash.

The method of analysis was precisely as in the foregoing instance.

23.645 grains of material gave when dried 21.670 grains, or 91.64 per cent., having lost 8.36 of water.

This residue gave 17.379 grains of palladium, being 73:49 per cent.; and then 4.569 grains of sulphate of barytes, being 19-36 per cent., containing 6'65 of sulphuric acid.

C. A portion of the same specimen having been exposed to the air for some time was analysed.

27.443 grains gave when dried 23·722 grains, or 86:45 per cent., having lost 13.55 of water.

This residue was ignited with carbonate of ammonia. It left 19.215 grains of metallic palladium, equivalent to 70.02 per cent.

This basic salt had, therefore, by exposure to the air, regained a quantity of water of which it had been deprived by the high temperature of the stove in which the drying of the precipitates had been effected.

D. Prepared by ammonia, not added in excess, and dried at 150° Fah.

I. 47.072 grains of material gave, by a temperature near, but. still below, redness in the dark, 40.361 grains of dry substance, being 85.74 per cent. It had thus lost 14.26 of water.

By fusion with carbonate of soda, and treatment in the usual manner, were obtained 32 444 grains of metallic palladium, and 9.800 grains of sulphate of barytes. These weights indicate 68.91 per cent. of metal, and 7.15 of sulphuric acid.

II. 24.780 grains of this specimen were heated until all water was given off; it then weighed 21·159 grains, having lost 14:58 per The dry salt was then exposed to a damp atmosphere for twenty-four hours; it did not increase very sensibly in weight. This basic sulphate has, therefore, no power to reassume the hydrated condition, having been once fully dried.

This dry material was fused with carbonate of soda, and the metal and sulphuric acid determined by the usual methods. It gave 16.977 grains of palladium, or 69-47 per cent., and 4.275 grains of sulphate of barytes, indicating 6'94 of sulphuric acid per cent.

The analyses A. B. and C. would tend to show that this salt may

exist in two degrees of hydration, but I rather think that the difference is not important, for in heating the other specimens I could not trace any distinct term at which an interruption to the evolution of the water occurred. In the first examples, the specimens had been dried in a stove at a temperature which would have probably rendered them quite anhydrous, had they been exposed to its influence for a much longer time.

I shall exhibit the results of all the analyses as follows:

It is thus abundantly evident that there exists but the one basic sulphate of palladium which may be prepared by the action of water or of any alkali upon the sulphate, and the analysis given indicate that the dry salt has the formula S O3 + 8 Pd O, from the per cent. composition of which none of the results found vary much; whilst the mean of all coincides completely with it. Thus,

The two hydrated states of this salt are accurately expressed by

the formulæ

SO3+ 8. Pd O + 6 H O, and S O3 + 8. Pd () + 10 H O, which give in numbers,

Of the Ammonia-sulphates of Palladium.

On adding water of ammonia to a solution of sulphate of palladium, no ammoniacal compound is at first obtained, but merely the basic compound already described. When, however, the ammonia is added in excess, the basic salt redissolves, and a colourless liquor is produced, from which the ammonia sulphate may be obtained crystallized, by cautious evaporation and cooling

This salt is best obtained by taking a strong solution of the neutral sulphate, and passing into it a stream of ammoniacal gas until the brown precipitate which first appears is totally redissolved; then filtering, if necessary, and seting aside to cool slowly. It then forms rectangular prisms, often of considerable size and of a beautiful pearly lustre.

When this salt is very gently heated, it gives off water, and the crystals become opake, but without losing their form or whiteness. Ammonia is next evolved, and the salt changes into a yellow powder, which, when more strongly heated, fuses, evolves sulphite of ammonia, ammonia, nitrogen, and water, and leaves a metallic palladium. A very finely crystallized specimen was analysed as follows :A. 25 987 grains decomposed by very full ignition gave 9.414 grains of palladium, or 36·24 per cent.

B. 48 677 grains dried at a very moderate heat as long as any water was evolved, but without any loss of ammonia, and remaining quite white, then weighed 45-672 grains, having lost 6.19 per cent. of water.

17.039 grains of this dry material gave by bright ignition 6:591 grains of palladium, which is 38.68 per cent. for the dry, and 36.28 for the hydrated salt.

C. 28 462 grains of the crystals were fused with carbonate of soda and the mass treated with boiling water. The metallic palladium which remained weighed 10.340 grains, or 36.50 per cent.

The alkaline liquor acidulated by nitric acid and treated with nitrate of barytes, gave 22.827 grains of sulphate of barytes, indicating 27.67 per cent. of sulphuric acid.

These results may be thus exhibited.

38.68

Palladium..... 36.24 36.28 36.50

These results abundantly show that the formula of this salt is,

when crystallized, S O3 + Pd O + 2 N H, + H O, which gives

I have shown elsewhere that the sulphates of this class must be considered as consisting of an ordinary ammoniacal salt united to a metallic oxide combined with ammonia, or to a true metallic amidide. Of these two states, the ammoniacal sulphates of copper and of silver afford examples, the former having the formula S O3. N H1 O + Cu O.N H3, whilst that of the latter is S O3. N H, O + Ag . N H2. The salt of palladium, at present in question, affords an excellent instance of the passage from one to the other state, for as the crystals lose their water by a gentle heat, and the quantity of it amounts to exactly an equivalent, the formula of the dried salt becomes S O.. N HO+Pd. N H2, and there is hence good ground for the opinion that the atom of water is really present as such in the hydrated salt, and that in this, and also in the corresponding salts of nickel, cobalt, copper, and zinc, the metal is truly combined with amidogene. The formula is then to be written for this, as for all such salts, S O3. N H, O + Pd. Ad + Aq.

There exists another ammonia-sulphate of palladium, which may be formed by the action of a moderate heat upon that already described, until it is totally converted into a yellow powder, or it may be produced by adding sulphuric acid to a strong solution of the preceding salt, or by boiling such solution for a long time. It then precipitatates as a yellow crystalline powder, which dissolves easily in boiling, but very sparingly in cold water. By a strong heat it is decomposed into water, and gaseous products, sulphite of ammonia, and metallic palladium.

It was analysed by fusion with carbonate of soda, treatment of the residue with water and determination of the sulphuric acid, as sulphate of barytes. From 27.103 grains there were thus obtained 12.128 grains of metal, or 44.70 per cent., and 26.886 grains of sulphate of barytes, or 98.8 per cent., containing 34.40 of acid. The formula deducible from these numbers is S O,. Pd O + N Thus there is

H3.

On adding muriatic acid to a solution of the white ammonia-sulphate it is not this salt which separates, but the yellow ammoniachloride already noticed.

(To be continued.)

•Transactions of the Royal Irish Academy," vol. xix., p. 77.