I have alluded to this cloud-formation before as characteristic of an early stage of the appearance of these figures, and as suggesting a process of condensation going on. Lombroso, from various considerations which he brings forward (p. 185),[112] seems convinced that the phenomena of these forms are largely connected with radio-activity. He says:—“It would seem that these bodies belong to that further state of matter, the radiant state, which now at last has established a firm footing in science—and which thus offers the only hypothesis which can reconcile the ancient and universal belief in the persistence of some form of life after death with the postulates of science which maintain that without organ there can be no function.” This radio-active condition of matter is of course that finest and most active state represented by the electrons—in which each electron is excessively minute,[113] yet moves at enormous speed, and carries with it an electric charge. It connects itself with condensation in this way, that “an electric charge assists vapor to condense,” and “where ions (_i.e._ positively or negatively charged particles) are present in considerable numbers a thick mist will form whenever the space is saturated with vapor.”[114] And Fournier d’Albe says:[115]—“In the physical theory of ionization and condensation we have become familiar with the fact that the smallest charged particles are the most effective promoters of condensation. In fact, it would suffice to extract a very small proportion of the innumerable electrons within the body to bring about a vigorous condensation in the moist air around it.” Thus it is quite probable that the cloud-formation, which in general precedes the manifestation of distinct figures, is due to condensation, and in part at any rate to a condensation of water-vapor on the accreting particles of the spirit-body. And this is made the more probable by the strong sensation of _cold_ which so frequently accompanies these appearances, and which is a common accompaniment of condensation. Crookes, in his _Researches_, emphasizes this in connection with almost all the phenomena, and says[116] they “are generally preceded by a peculiar cold air, sometimes amounting to a decided wind. I have had sheets of paper blown about by it, and a thermometer lowered several degrees. On some occasions ... the cold has been so intense that I could only compare it to that felt when the hand has been within a few inches of frozen mercury.” Some such sensation seems to be quite a common experience, and the authoress of _Shadowland_, speaking of her earlier sittings (p. 228), says:—“It was not long before the same strange disturbances in the air began as on the previous occasion. I felt my hair blown and lifted by currents of air, and cool breezes played about my face and hands.”