536 



NATURE 



[April ^, 1888 



should be read, a multiplie'd by /;, the symbol a.b or ab should 

 mean a multiplied into b, so that ax. b and b.a or ab are identical. 

 Perhaps a compromise might be effected on this basis in the 

 notation of quaternion multiplication. 



The "unnained French mathematician " who is quoted in the 

 notice in question as asserting that quaternions have no sense in 

 them, is stated by M. Laisant to have been M. Prouhet, and 

 to have expressed this opinion in the Nouvelles Antiales dc 

 Mathematique (1863, p. 333), in reviewing the first work 

 published in French on quaternions, the author of which was 

 M. Allegret. W. Steadman Alois. 



Auckland, New Zealand, February 20. 



Mr. Crookes and the Transformation of Heat- 

 Radiations into Matter. 



Prof. Clifford, in the Fortnightly Review, June 1875, 

 wrote as follows : — "But if the ether did absorb light, what 

 would this mean? Vibratory motion of solids, which is really 

 a molecular disturbance, is absorbed by being transformed into 

 other kinds of molecular motion, and so may finally be trans- 

 formed to the ether. There is no reason why the vibratory 

 motion of the ether should not be transformed into other kinds 

 of ethereal motion ; in fact, there is no reason why it should not 

 go to the making of atoms " (" Lectures and Essays," by W. K. 

 Clifford, vol. i. p. 246). 



Mr. Crookes, in his Presidential Address to the Chemical 

 Society, March 28, brought forward a somewhat similar hypo- 

 thesis, for he says : — " If we may hazard any conjecture as to 

 the source of energy embodied in a chemical atom, we may, I 

 think, premise that the heat-radiations, propagated outwards 

 through the ether from the ponderable matter of the universe, 

 by some process of Nature not yet known to us, are transformed 

 at the confines of the universe into the primary — the essential — 

 motions of chemical atoms, which, the instant they are formed, 

 gravitate inwards, and thus restore to the universe the energy 

 which otherwise would be lost to it through radiant heat." 



The hypotheses will be seen to be exactly alike, except for the 

 speculation introduced by Mr. Crookes of the transformation 

 taking place "at the confines of the universe." What do we 

 know of the confines of the universe ? Nothing. Are we now 

 to begin building up hypotheses on such foundations — foundations 

 concerning which we know nothing, and are not likely to know 

 anything/(?r some time i Hugh Gordon. 



Royal Institution, March 31. 



Green Colouring-matter of Decaying Wood. 



Mr. Irving writes (p. 511) : " After an examination of thin 

 sections " of the decaying wood "with the microscope, I am 

 unable to trace this to any saprophytic organism." 



I have at the present time a coccus, I suppose, growing on the 

 surface of nutrient gelatin, which is stained a beautiful green, 

 highly fluorescent, by the colouring-matter absorbed by it from 

 the micro-organisms. The cultivation is in a test-tube of nutrient 

 gelatin inoculated by scratching the surface of the gelatin with a 

 needle which had been rubbed on a colony, isolated by plate- 

 cultivation, and obtained from a bad water. 



The growth, a greenish- white, is entirely on the surface — so 

 entirely that the scratches made in inoculating the gelatin are 

 still visible, three weeks after the inoculation, and the gelatin is 

 perfectly transparent. 



Under these circumstances it is quite certain if I made sections 

 of the green gelatin no micro-organisms would be found in 

 them. 



It may be that the decaying wood is stained in the same way 

 by colouring-matter absorbed by the sap or the moisture of the 

 wood by micro-organisms growing on its surface. 



It is a fact, I believe, that the colouring-matter formed by 

 chromo-genic micro-organisms does not reside in their structures 

 but in the interspaces between them, so it would naturally be 

 absorbed by any solvent they were in contact with, while the 

 organisms themselves might remain entirely on the surface,as they 

 do in the case of my gelatin. 



This may explain why Mr. Irving has failed to find micro- 

 organisms in the sections he made. Further, if the colour of his 

 green woud is caused by the same micro-organism which stains 

 my gelatin green, it is a very small one, so small that, with 

 a i/15-iuch oil-immersion object-glass, and a No. 12 compensat- 



ing eye-piece of Zeiss, I find it very difficult to decide what shape 

 it is, but I think it is not spherical. 



I think Mr. Irving will find references to the literature of 

 chromo-genic micro-organisms in Crookshank's " Manual of 

 Bacteriology." Henry Robinson. 



The University Chemical Laboratory, Cambridge. 



Comet a 1888 (Sawerthal). 



I SAW comet Sawerthal to-day at 3.40 a.m., with power 20 

 on a 4j-inch refractor. It was about 50' immediately below 

 Pegasi, and had a bright broad tail, which I could only dis- 

 tinguish to a length of 65', on account of the twilight, moon- 

 light, and the comet's low altitude. I thought the tail was 

 slightly curved, concave to south ; it pointed on the average to a 

 little above v Pegasi, or at a position-angle of about 260°. The 

 total light of the head was considerably fainter than Q Pegasi, 

 and considerably brighter than v, so that it would be from 4 to 

 45 mag. ; but owing to the unfavourable conditions I could not 

 see it with the naked eye. T. W, Backhouse. 



Sunderland, April 3. 



THE HITTITES, WITH SPECIAL REFERENCE 

 TO VERY RECENT DISCOVERIES^ 



IL 



THE monuments at Boghaz-Keui and Eyuk are on the 

 east of the River Halys ; and it seems doubtful 

 whether there is evidence that the country inhabited by 

 the Hittites extended much, if at all, beyond a line drawn 

 from Sinope on the Euxine to the most westerly bend of 

 the Halys, and continued through the peninsula to the 

 Mediterranean. No doubt sculptures with Hittite cha- 

 racteristics have been found further to the west, as at 

 Giaour-kalessi, in Phrygia, and at Karabel, near to 

 Smyrna and to the coast of the ^gean ; but as yet it does 

 not appear certain that these sculptures denote permanent 

 occupation, or that they are more than monuments of 

 successful military expeditions. The Euphrates may be 

 taken as marking vaguely the eastern boundary of the 

 Hittite land. To the south, in Syria, the Hittite country 

 certainly extended as far as Kadesh, a site on or near the 

 present Lake of Horns. 



It is with the inscriptions and the engraved seals found 

 in, or connected with, the district I have indicated that 

 Hittite researches are mainly concerned. The few 

 characters on the monument at Karabel are too far 

 obliterated to be, for the present, of much importance. 

 In 1812, Burckhardt visited Hamah, the ancient Hamath, 

 in Syria. He saw in the corner of a house in the bazaar 

 " a stone with a number of small figures and signs, which 

 appear to be a kind of hieroglyphical writing, though it 

 does not resemble that of Egypt " (" Travels in Syria," 

 Lond., 1822, p. 147). But, as Dr. Wright remarks, "so 

 little interest was taken in his discovery, even by pro- 

 fessional explorers, that Porter, in Murray's ' Hand-book,' 

 so late as 1868, declares 'there are no antiquities in 

 Hamah'" ("Empire of the Hittites," 2nded.,p. i). There 

 were, however, other inscriptions at Hamah besides that 

 noticed by Burckhardt, and the stone bearing one of 

 these was supposed to possess mysterious properties, 

 efficacious for the cure of spinal disease, so that " de- 

 formed persons were willing to pay for the privilege of 

 lying upon it, in the hope of a speedy cure " (Burton and 

 Drake, "Unexplored Syria"). After sixty years, or 

 nearly so, from the time of Burckhardt's discovery, 

 attention was called to the Hamath inscriptions, first by 

 Mr. J. A. Johnson, United States Consul at Beyrout, and 

 subsequently (1872) by Capt. R. F. Burton and the late 

 C..F. Tyrwhitt Drake, in the work just quoted. In 1872, 

 however, Dr. Wright was successful in obtaining casts of 

 the Hamath inscriptions, while the originals were trans- 



I Based on Lectures delivered by Mr. Thomas Tyler atthe British Museum 

 in January 188S. Continued from p. 514. 



