cessary conditions being fulfilled for the condensation of aqueous vapor. The same thing happens at the inlet and outlet of the holders, and the outlet governors, but to an extent less perceptible, inasmuch as the entire mass of the gas does not come in immediate contact with the water. These observations are the result of notes made in the works which I direct, when, as I have said, the production of naphthaline is considerable; this is due, perhaps, to a cause which I have not made known here, although it may be a strong argument in favor of the theory of which I sustain.

sure.

I will cite one case. On the first of December a new station meter, with new outlet and inlet pipes, was placed in service. Although this meter measured, each day, a volume of gas considerably above that for which it was built, still, it absorbed only fifteen millimeters of pressure. On the first of January, following, one month after, it absorbed 170 millimeters of presIts outlet pipe was lined all around (bushed, literally), with C1H, its inlet, though spangled with naphthaline was, relatively, free from it. It is useless to say that the meter was filled with pure water. Why are the covers of the two purifiers spangled with sublimed naphthaline on the inside? Why is the surface of the material in the boxes covered with naphthaline? It is because the gas on leaving the boxes, saturated with aqueous vapor change of velocity finds a condensor with a large surface abandons a part of its aqueous vapor, and the proof that it abandons a part of this vapor is, that if the gas enters from above, the surface of the material is damp, wet, and that in descending through the interstices, the dampness diminishes, disappears towards the middle and reappears again below, near the bottom, which is a new condensor cooled by the soil, or the current of air in the cellar under the purifiers. Leaving these, naphthaline reappears, obstructs the outlets of the boxes, and its deposit, as I have said, goes on diminishing to the apparatus, which follows where the gas reabsorbs all the quantity of water which it has given up en route, gives it up again by condensation, and will deposit anew more naphthaline in some conditions, such that the first deposits of it which have taken place would not permit us to suppose that it ex

isted still.

The anaylsis of illuminating gas does not show the presence of naphthaline. I speak only of such analysis as have been made up to the present time, and do not refer to the new communications made by Mr. Berthelot, to the Academy of Sciences, which permit us to believe that illuminating gas is only composed of vapors. The experiments of Pitschke, cited in Schilling, are the only ones which established the existence of naphthaline in gas. I shall discuss these experiments further on. It is easy to prove that the CH, which Pitschke has found, did not pre-exist, and that the nature of the conditions to which he submitted the gas, had given birth to it for him. Analysis of gas shows the presence of ethylene, of butylene, of acetylene, of marsh gas of the oxide of carbon, of carbonic acid, of hydrogen, of nitrogen, but not of naphthaline. Naphthaline does not pre-exist, then, in gas. It forms itself there, and under certain influences. No more does benzine pre-exist in gas, for it would dissolve the naphthaline in it, either that which the gas contained, or that deposited in the pipes; analysis, moreover, does not show its existence in it. However,

in the street mains we find naphthaline in dangerous propor: tions, and in the drips we detect the presence of benzine. Both are produced under the same circumstances, and under the same influences, but with this difference always, that naphthaline can be produced from benzine, and that benzine cannot be produced from naphthaline. If I establish this parallelism between the two bodies, that is, that the igneous reactions of which I have spoken above, make known the relative relations existing between them, and that it is thus that I happen to establish the production of naphthaline in the gas, and consequently that it did not pre-exist there. I will describe an interesting fact that I have observed, and that I think it necessary to make known.

Upon one of the main outlet pipes of my works, whose diameter is 350 millimeters (14 inches), I have had a branch at a distance of 1,200 meters from the point of departure, a new condiĉt of 300 millimeters in diameter, which is supplied only from a single point and at intermittent periods. In one place, this pipe, which was only .80 C. below the surface, de

scended, by necessity, to a depth of four meters (five feet), and this for 700 meters nearly to its junction. The syphon that this difference of level necessitated was always filled with a blackish liquid, very rich in benzine, while the syphons at the outlet of the works, and of the main pipe which supplied this branch, gave only water with some traces of light oil. This tends to prove that the gas that sleeps, so to speak, in this pipe of 300 millimeters, unused at certain times, and sometimes for long periods, undergoes certain influences in which time also acts, gives birth to benzine, and that it did not pre-exist since, through all the course of the gas before the point, that is to say, for a length of nearly two kilometers (five miles), we find in the liquids of condensation only mere traces of benzine (CH). I have said that the experiments that I made established the fact that gas, entirely dried, entirely deprived of aqueous vapor, could not deposit naphthaline. The following are the experiments:

1st. I took upon the same current of gas, two branches, one which conducted the gas in its ordinary state, in the other it passed successively through three flasks containing each one kilograme of chloride of calcium, in such a way that the gas was entirely dried. When the first flask became wet I renewed the chloride of calcium that it contained. The gas from each of these two branches followed the same course in glass tubes, kept parallel, which were joined to a series of Liebig tubes, which were plunged into the same salt bath, kept constantly at a temperature of 70° Cent. Upon leaving the bath the gas circulated in parallel tubes and entered a new series of Liebig tubes, plunged in the same receiver filled with ice, and sometimes with a refrigerating mixture, at the outlet of which, after passing over an identical course, I caused the dry gas to absorb water by simply flowing through it. The gas thus restored to state of ordinary moisture returned by similar tubes to the first, into the same salt bath which it passed through, in like Liebig tubes. I reproduced, in this way, in an exaggerated form, what actually occurs in practice, the gas passing suddenly from a high temperature to a very low one, and changing velocity in consequence of the change in section of the pipe.

It is useless to say that I operated upon gas perfectly purified, and that the quantities of gas with which I experimented were equal.

This experiment lasted for a month, and that, too, in the same month of December that the same gas produced an engorgment from naphthaline, in the outlet of the station meter of which I have spoken. That upon which I experimented was taken off before it arrived at this apparatus. Let us look at the results. I never obtained a trace of condensation, or a trace of naphthaline in the tubes through which the dried gas passed. I did obtain condensation, and always naphthaline, not only in the tubes where the gas was not dried, but also in those tubes where the gas dried at first had given none, but had retaken moisture from the last flask.

I think this first experiment conclusive, and I add that the dried gas had gained in illuminating power, as was easy to for

see.

Second Experiment—As I said before, naphthaline made its first appearance in my works, in a considerable quantity, upon the surface of the purifying material in the boxes, and upon the interior of the covers. One of these, in particular, permits. the crystallization of naphthaline to take place in proportions, such that we cannot think that the naphthaline was produced far away, for it would all have stopped there if this naphthaline had pre-existed in the gas. I divided this box in two parts. In one of these parts the oxide of iron was left as usual, in the other part I put a layer of oxide of iron 20 centimeters thick, and then placed quicklime upon this for a height of 20 centimeters. At the end of several days I raised the cover of the box. The surface of the half of that I had left in the ordinary condition (the oxide of iron part) was literally covered with naphthaline, and the corresponding part of the cover was spangled with it.

The part where I had placed the quicklime had not a trace of naphthaline, and the half of the cover over the quicklime had not a trace of it. The box was worked equally in other respects, that is to say, that below the 20 centimeters of lime, upon leaving the point where the whole box was filled with

oxide of iron in the ordinary state, the material was blackened equally over the whole surface of the box, and at the same height. The lime was partially slacked by the water of the gas which it had absorbed. Thus, the surface of the material and the cover of the box, showed the contrast of being upon one part, entirely dry and free from naph haline, while upon the other part, naphthaline was perfectly sublimed in brilliant and moist particles.

A third experiment, which is a reproduction, upon a large scale, of the first, is now in progress, but I cannot now make known the results, as I intend to make it last for several months.

I feel authorized to quote from a letter that I have received from one of my colleagues, the manager of a large works, in which the purification is by lime exclusively, not quicklime, but lime slaked in powder, and susceptible still of absorbing a considerable quantity of aqueous vapor. I quote literally from this letter, which was not written. by request, the author being ignorant of my experiments, and the theory which flows from them. "I must tell you, first of all, that my condensing apparatus is sufficiently powerful, and that, consequently, deposits of naphthaline sufficient to produce an obstruction in the ordinary working are very rare. My purification is still entirely by lime. I have little or no naphthaline at the inlet or outlet of my purifiers, and it is only from sense of duty that I overhaul this part of my pipes once a year.

"I have more of a deposit at the inlet of the station meter, and above all at the outlet."

I underline these last words, which confirm my statement, that naphthaline is produced at the outlet of an apparatus in which the gas is saturated with the vapor of water, and when it gives up this vapor by condensation. The influence of condensation of aqueous vapor contained in the gas upon the production of naphthaline is then evident, and demonstrated by these experiments. This is the third cause, of which I spoke at the commencement of this memoir. It is only explained by the reproduction in the mass of the gas of reactions,