Sometimes it happens, that it is no longer the effluvium which is perceived, but the whole hand itself becomes phosphorescent. Rays come and go like gleams on the back of the hands, or on the fingers, and sometimes, but very rarely, on the face or body of the sitters. These phosphorescences and the digital effluvia appear to me to belong to the same order of phenomena. Frequently, they are but fleeting gleams seen at the finger-tips, when the hands are resting on the table. Though I and others who have experimented with me, have often verified this appearance, I have some doubts upon its reality. In obscurity, the eye tires quickly, and phosphenes soon appear; still, I have nearly always observed, that these glimmering lights were perceived by other persons in the same spot I saw them in.
I have rarely observed those glimmering lights, some people see, on the garments and faces of sitters.
I have not yet been able to verify, in a positive manner, the phosphorescence of the hands in ordinary seances; though observers in whom I have the greatest confidence, have assured me that they had remarked it. We must not lose sight of the fact that the eyes tire quickly; when the obscurity is not complete, the white hands are vaguely perceived on the dark background, the eyes, growing tired, accentuate the contrast between the two shades, and the palest has a tendency to appear slightly luminous.
Sometimes, but very seldom, I have observed sparks which seemed to coincide with raps. This phenomena appears to have an objective reality. I was not the only one to notice these sparks; others saw them also; their apparition at the moment the raps were heard was constant. These circumstances permitted us to think, that the phenomenon ought to have an objective substratum of some kind.
However, I have observed luminous phenomena which were decidedly objective. At Choisy, we obtained them under special conditions, which Rochas has indicated, and which are rather significative. These lights, which were very brilliant, looked like large phosphorescent drops gliding about on Eusapia’s bodice, after having floated for some time in the air. This phenomenon did not appear to me to be very convincing, because during the sitting, a strong odour of phosphorus permeated the room. When Eusapia had left, I returned to the room, where I found MM. de Gramont and de Watteville, who were as inquisitive as I was. We searched but found nothing on the floor.
Our suspicions had been aroused by the phosphorescent odour, which was diffused in the room. Since then, I have noticed it in seances, where fraud seemed to be impossible. This odour is characteristic; it is more like the odour of ozone than that of phosphorus. It is like the odour perceptible in the vicinity of static electrical machines when in activity.
These flitting lights can be easily imitated. A prudent experimenter ought never to lose sight of the fact, that it is possible to employ diverse substances in order to produce phosphorescent effects. The use of phosphorescent oil, for example, will give fictitious luminous phenomena. I remember a seance at which the medical student, of whom I have already spoken, was present. I noticed that one of his finger-tips shone for a moment. I afterwards learnt, that this young man had a phial of phosphorescent oil in one of his pockets. On another occasion, long narrow lights were, from time to time, seen on his body. I think these were produced by matches or straws dipped in the luminous liquid. Phosphorescent preparations, as a rule, have the advantage of only becoming very luminous, when they are shaken about in the air; for the lights, which are given forth by the phosphorus they contain, are only produced when there are phenomena of oxydation.
Objects coated over with sulphide of calcium, strontium, or baryum, become luminous in obscurity, when they have been previously exposed to light. This is the principle of luminous dials, match-boxes and candle-sticks. There are also other substances which permit of simulating luminous phenomena.
I was once present at some seances, which were very curious from the point of view of the luminous phenomena which I observed. These seances were of the series of which I have already spoken. The two young tricksters, some of whose misdeeds I have related, were present, and as one of them is an excellent chemist, it is possible that the superb phenomena I observed were not altogether authentic. I confess, I do not see how fraud was committed; but, given the conditions under which I experimented, I think I ought to abstain from expressing a favourable opinion upon the reality of the facts observed. I will describe them succinctly, indicating the phenomena which could have been simulated, and those which did not appear to be so.