JiNE 1, 1892. J 



KNOWLEDGE 



107 



more than an accidental one caused by similarity of habitat. 

 Mr. Hardy, speaking of one of these root-feeding species, 

 says, "When Fotihi formicdiin (the aphis) prevailed in the 

 nests of Formiin fuUyinosa, I noticed that the Ants paid no 

 attention to thexi when the hillocks were disturbed. The 

 aphides slowly re-covered themselves with earth, and those 

 which failed to do so were left quite unnoticed by the 

 numerous Ants running about them." In other cases, 

 however, the aphides were carried off by the Ants, a good 

 deal of persistency being manifested by them in doing so. 

 Mr. Buckton surmises that these wingless subterranean 

 aphides may ultimatsly turn out to be secondary forms 

 (dimorphs) of species whose winged forms are found above 

 ground. 



Aphides are not the only bisects whose glutinous 

 secretions are palatable to Ants. M. Niceville, ia the 

 " .Toumal of the Bombay Natural History Society," describes 

 the caterpillars of certain butterflies belonging to the 

 Ljicanidir, found in India, which secrete a sweet liquid 

 from an oval opening on the back of the eleventh segment 

 of their body. The Ants are fond of this liquid and excite 

 its flow by stroking the caterpillars with their antenna'. 

 They are said to arrange a sort of earthen nest, with stalls 

 in it, at the foot of the tree on which the caterpillars are 

 feeding, and when the caterpillars are about to pupate, to 

 lead and drive them into this, so that they may be 

 protected when in their helpless pupahood. When the 

 time comes for the issue of the butterfly, it is helped out of 

 its shell with tender care by its guardians, but if it should 

 prove a cripple, they bite off its wings and carry the body 

 into their nest, possibly to use as food. Other insects, 

 also, especially some belonging to the Homoptera or Frog 

 hoppers, are valued by Ants for secretions which they 

 supply. 



To conclude then, it appears from what has been said 

 above, that the relations between Ants and other insects 

 are of the most varied and complex character ; the more 

 they are studied, the greater seems to be the variety. 

 Much yet remains to be discovered — in fact, the unknown 

 probably far exceeds the known — so that here is a tempting 

 field of observation for anyone who has the corn-age and 

 opportunity to enter upon it. M. C-arpentier has very well 

 summarized some of the chief facts so far as at present 

 known, and with an extract from his summary we will 

 close this paper : " Some insects live side by side with 

 Ants of all kinds, because they have the same habitat, 

 the bark of fallen -trees, old stumps, flat stones, moss, kc. 

 Mutual forbearance is then the order of the day ; and the 

 necessary neighbourly feelings are maintained, while at 

 the same time the rights of all are respected. But other 

 insects are attracted by the kitchen stores of the Ants, by 

 their refuse matters, by the different materials that they 

 use in their building operations, or by other unknown 

 causes, whether casual or constant. They may also be 

 born in the .\nt-hiUs, having been brought in uninten- 

 tionally by the Ants in one of their earlier stages, along 

 with the provisions which they go out to collect from a 

 distance." 



PHOSPHORUS MIRABILIS. 



By Vaughan Cornish, B.Sc, F.C.S. 



ANY substance capable of shining in the dark was 

 originally termed a phosphorus. Several sub- 

 stances having the property were known as early 

 as the middle of the seventeenth century, such, 

 ■ for instance as barium sulphide, the "Bonnonian 

 Phosphorus," to which may be added the sulphides of 



calcium and strontium. The power of barium sulphide 

 and similar bodies to phosphorexir depends upon their 

 being previously exposed to light. When a ray of light 

 falls on any substance, part is reflected and part absorbed. 

 As long as the body is exposed to the ray of light it is 

 itself a source of luminous disturbance, and consequently 

 a visible object. The peculiarity of substances such as the 

 sulphides of the alkaline earths is that they continue to 

 be a source of luminous disturbance for a time, when no 

 longer exposed to the ray of light. This power of a body 

 to store up, and slowly dole out the luminous vibrations it 

 receives is called, in physical optics, phosphorescence. 



Bodies having this property are termed phosphorescent 

 bodies. 



Of all substances luminous in the dark, common yellow 

 Phosphorus is the best known, and the example which 

 most people would cite as that of the typical phosphor- 

 escent body. Singularly enough, the causes which induce 

 the glow of the chemical element Phosphorus are 

 altogether distinct from those we have mentioned as the 

 cause of phosphorescence in barium sulphide and similar 

 bodies. The terminology of the subject has undergone a 

 pecidiar alteration since the seventeenth century. At that 

 time any substance capable of shining in the dark was 

 called "a Phosphorus." Now, the name Phosphorus is 

 restricted by chemists to one chemical element. The 

 element in question exists in more than one allotropic 

 modification, and one of these forms (red, or amorphous, 

 Phosphorus) does not shine in the dark. 



While, on the one hand, chemists have made the term 

 Phosphorus special, instead of generic, physicists usually 

 apply the term phosphorescent to a whole class of sub- 

 stances ; but " Phosphorus " does not belong to this 

 class. 



In the present article we will give a short sketch of the 

 investigations which have been made into the subject of 

 the " Glow of Phosphorus." Ordinary yellow Phosphorus 

 was first prepared by an alchemist of Hamburg named 

 Brandt, and in spite of the care with which the secret of 

 its preparation was guarded a number of persons soon 

 became possessed of the method of manufacture. The 

 early methods, however, gave but a small yield, and were 

 so difficult to carry out that the substance remained for 

 long an extremely expensive chemical curiosity. Its many 

 remarkable properties were a favourite subject for exhibi- 

 tion among the learned and curious, and earned for Brandt's 

 production the name of the I'hosphnrus miniliilis. Robert 

 Boyle observed that the ['hosphorus mirnhilis difi'ered from 

 other shining bodies in that its luminosity did not depend 

 upon its being previously exposed to light. Subsequently 

 it was observed that if Phosphorus were brought into the 

 vacuous space above the mercury in a barometer tube the 

 body no longer shines in the dark. It seemed probable, 

 therefore, that the glow was induced by the presence of air. 

 As in most phenomena in which air takes part oxygen is 

 the active agent, it appeared likely that the glow was due 

 to some action between the Phosphorus and the oxygen of 

 the air. It was found that in pure oxygen Phosphorus at 

 the ordinary temperature and pressm-e did not glow at all. 

 The glow can, however, be induced either by " partially 

 exhausting " the oxygen in the vessel {i.e., by diminishing 

 the pressure), or by raising the temperature. If after the 

 latter means had been adopted the oxygen were compressed, 

 the glow again disappeared. Now, at the ordinary tem- 

 perature Phosphorus volatilizes, or evaporates at a very 

 appreciable rate. From these facts, therefore, it seemed 

 probable that the glow was due to an action between the 

 vapour of Phosphorus, and oxygen, the two factors 

 essential for the production of the glow being the presence 



