nesia, potash, soda, and even ammoniac, since Prussian acid can likewise take away all these bases from their dissolvents when the sum of the various affinities is in its favour.

I have proved this in potash by the experiment stated above, where it has been shewn that it separated the Prussian acid from lime by giving up its carbonic, acid.

The effect is still more speedy with carbonate of sodą and prussiate of lime.

The solution of nitrate of strontian is likewise decomposed by the prussiate of lime,

If a few drops of prussiate of lime be added to a solution of sulphate of ammoniac, in about five or six minutes you observe floating on the surface a whitish frothy scum, six or seven millimetres in depth, which deposits small flakes.

Lastly the mixture of sulphate of magnesia and prussiate of lime becomes muddy in the same manner in a few minutes, and forms a precipitate.

Let us then return to the real cause of these phenomena, the power of double attractions for which we are still guided by the simple elective attractions, the order of which is wholly independent of the series in which we place such substances as have several properties in common. Thus barytes should no more be placed before potash in the table of Prussian acid than lime before fixed alkalis in tables of oxalic, tartaric, boracic, &c. acids. It is therefore with much greater propriety that it is proposed to class barytes with alkalis, which it resembles in point of chemical action in a great variety of circumstances, but from which it is distinguished, as I have said elsewhere, by some characteristics which may be considered decisive, and especially by its insolubility in alkohol.

Report

Report on a Memoir sent to the Society of Apothecaries of Paris, by M. Robert, of Rouen, on the Inflammation of combustible Bodies by their contact with Sulphuric Acid; with additional Experiments. By Messrs. CHARLES LOUIS CADET, and BOULLAY.

From the ANNALES DE CHIMIE.

M. ROBERT recapitulates the different experiments

made by Messrs. Fourcroy and Vauquelin on the effects of super-oxygenated muriate of potash combined with certain combustible bodies and submitted to the action

of shaking or friction. All chemists are now acquainted with those beautiful explosions, and the inflammation produced by the same bodies when plunged in concentrated sulphuric acid is likewise familiar to them. The latter experiments are modified by M. Robert in an interesting manner. Instead of throwing the inflammable mixtures into that acid, he only touched them with a tube dipped in it. In this manner he inflamed :

1. Three parts of super-oxygenated muriate and one part of sulphur.

2. Three parts of the same salt, half a part of charcoal and the same quantity of sulphur.

3. Equal parts of antimony and super-oxygenated muriate.

4. Equal parts of sulphur, antimony, and salt.

5. Equal parts of kermes and sulphur.

6. Equal parts of arsenic and salt.

7. Three parts of muriate and one of sugar.

8. Three parts of muriate and one of charcoal.

9. One part of muriate and three parts of gunpowder. 10. One part and a half of muriate and three parts of gunpowder.

Ddd 2.

Lastly

Lastly, compositions of alkohol, olive-oil, and superoxygenated muriate of potash.

We have repeated all these experiments with perfect success; and likewise the following, which justly appeared to M. Robert to deserve some attention.

He charged a pistol with common powder; he put into the pan the above mentioned mixture of powder and muriate; he set it on fire with the sulphuric match, and the pistol went off.

M. Robert observes that the brightness and colour of the flame, and the smell proceeding from different combustibles, differ essentially; but he did not endeavour to ascertain what gases were formed and what residuum remained after inflammation. We intended to have collected the gases produced, in an hydro-pneumatic apparatus, for the purpose of examining them; but the time fixed by the Society for making our report being only a few days, we postponed those researches.

Although these experiments appear calculated only to gratify curiosity, yet we determined to try in the same manner various simple and compound substances, on the inflammation of which no experiments had yet been made.

New experiments made by the Commissioners.

As the method of operation is nearly the same, to avoid incessant repetition, we shall only mention the substance combined with the super-oxygenated muriate of potash. Phosphorus affords a beautiful deflagration: hydrogen gas takes fire. To perform this experiment we filled a bladder with inflammable air, and to its mouth we screwed a copper tube. This tube was dipped in sulphuric acid and brought in contact with super-oxygenated muriate of potash, pressing the bladder at the same time that

the

the current of gas might be discharged on the salt. At the moment of contact the gas took fire as by an electrical spark.

Gold, silver, zinc, and iron, presented no other phenomenon than the decrepitation of the muriate only. The negative result did not surprise us with regard to the two first metals which are not easily oxydable; but zine and iron led us to expect an inflammation, as they detonate with a shock.

Brown oxyd of copper, the residuum by distillation of acetite of copper, burned without flame, but with flashes like artificial ones.

Metallic sulphates succeeded perfectly well, especially sulphate of tin, or black sulphate of mercury. The latter gives a very beautiful brilliant flame. Amber, acid of amber and coal, are not set on fire, but their decrepitation is very considerable.

Among vegetable substances there are some which take fire easily, as volatile oils, resin, turpentine, gum copal, gum arabic, powder of lycopodium, camphor, cotton, soap, sawdust. With the last mentioned material success is not always sure; but by adding a small quantity of sulphur an excellent fusing powder is produced that may be useful to mineralogists from the facility with which they may be inflamed by means of a re-agent.

We tried starch; it is difficult to inflame it, but we succeeded in making it burn. Ether takes fire very quickly; in this experiment, as well as in that with cam phor and alkohol, we observed that the super-oxygenated muriate was but very partially decomposed, that it did not burn, but served only to promote the inflammation. To ascertain this fact we mixed sulphur with the residue of this experiment, and a sulphurie match produced a socond combustion.

We made a paste of super-oxygenated muriate of potash and honey; this mixture inflamed with ebullition, emitting a smell of sugar-candy, mixed with a very penetrating acid which we imagined to be acetic acid.

Crystallized benzoic acid emits a considerable flame, of a reddish colour; tartaric acid, likewise, burns very well; the tartrite of pot-ash gives a whitish flame; tartrite of soda presents neither inflammation nor light. The antimoniated tartrite of pot-ash gives beautiful sparks without flame.

Oxalic acid, with oxygenated muriate, sparkles without inflammation. Acetic acid produces a considerable deflagration, and a bright, blueish flame. The acetates of pot-ash and soda take fire with a cracking.

These results induced us to try what animal matters might be inflamed by the same processes; we tried, without success, dried gluten, and hartshorn shavings.

The yolk of egg, wax, butter, grease, and suet, burned like oil, but with a greater cracking: wool, and a piece of rabbits' skin with the down, and thoroughly impregnated with super-oxygenated muriate of pot-ash, took fire and burned till they were entirely consumed.

Amongst the experiments which afforded some remarkable singularities, we ought to mention, that we could never inflame the fulminating powder; although decomposition, as well as an abundant disengagement of gas and heat, took place. Three other mixtures with metallic bases, likewise surprised us by their alarming explo< sion, their rapid inflammation, and their powerful effect in fire arms, exploding like powder by a spark from the flint. M. Robert undoubtedly tried them, but he makes no observation on the subject: in this respect we shall follow his example, and make but two remarks. Firearms are much oxydated, and destroyed in a short time

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