The air of the rooms has not been analyzed yet, and theory alone can guide us. If we examine one after the other, each of the substances which enter in the composition of the mastic, if we put aside the sulphur which plays no part, we find phosphorus alone which can change the atmosphere. We have demonstrated (Chap. I.) the facility with which phosphorus absorbs the oxygen of the air. At the ordinary temperature, the action of the air, principally damp, on phosphorus is very appreciable. If the air is dry and the temperature low, the action is but slightly perceptible; but, if damp, we see the phosphorus immediately surrounded by a light white cloud. These vapors are called hypo-phosphoric acid.

In aerated water exposed to the light, phosphorus gives phosphorous acid, and hydrogen proto-phosphuretted, produced by the decomposition of water, and there is not the least doubt that in the rooms some phosphuretted hydrogen is mixed with the hypophosphoric acid.

Another interesting question is, to know if phosphorus itself exists in a gaseous state in the atmosphere of the factory. Some chemists admit its existence. M. P. Thenard does not believe that the slow combustion of the phosphorus in the air is perfect, and he thinks that there is much vapor carried away at the state of phosphorus. The following facts demonstrate this theory: 1st. If a piece of phospho-rus is introduced for a few minutes into nitrogen, hydrogen, carbonic acid, etc., then taken out, and a little air introduced into the gas, it becomes luminous in obscurity; 2d. If we suspend to a thread a piece of phosphorus, and wo introduce it into a bottle and leave it in for a few minutes, the bottle stays luminous for some time, while containing a large quantity of oxygen. Thus phosphorus, while cold, emits vapors in gases, and this vapor is not instantaneously burned by the air. It is very probable that in the factories the workmen breathe vapor of phosphorus mixed with hypophos-phoric acid.

Let us examine now briefly the effects of these emanations on the health of the men.

The diseases are, 1st, more or less aggravated inflammation of the bronchia; 2d, alterations of the teeth and maxillary bones, etc.

1st. Bronchitis. - Coughing is the most frequent pathological phenomenon in the shops, but it is rare that the inflammation becomes great.

2d. Diseases of the Jaws. - It is not long since this disease has appeared amongst the men working in match factories. Dr. Strohl has pointed out in the following terms, the causes of this disease:-

"The vapors of phosphorus are transformed by its contact with oxygen into hypophos-phoric acid, and this acid mixed with the air is dissolved in the saliva, and forms phosphoric acid. Often this latter acid is produced by the combustion of the phosphorus, for it sometimes occurs that the vessel in which the mass is heated, takes fire. This substance renders the saliva acid. We know the dissolving action of this acid; the gums are softened by the saliva, the liquid acid attacks the teeth, filters between them and the soft parts, reaches as far as the alveolus, and there exercises its dissolving and corroding action.

This theory has not been admitted by all physicians, for the reason that if the theory were correct it would seem that the teeth would be invariably in a bad state, and it has been observed that in the same room, while one man has all his teeth destroyed, another working near him has them in perfect order.

It would be interesting and important, as well for science as on the score of humanity, to discover and point out the real causes of these diseases, and the proper mode of treating and curing them.