Auorsx 11. 1888.) 



THE GA RDE NEBS' CHRO NI CL E. 



151 



had experimented on the " fixed air " given off - during 

 fermentation ; had also, in 1772, examined azote, 

 and at Birmingham, on August 1, 1774, he made 

 his important discovery of the air we now call 

 oxygen. He called it dephlogisticated air. The 

 following year it was independently discovered by 

 Scheele in Norway. He called it empyreal air. 

 From the discovery of oxygen the new chemistry 

 took its rise. Priestley's statue at Birmingham 

 represents him in the act of making his discovery. 

 It is on record * that he first obtained it (in a closed 

 vessel heated by a burning lens), from minium com- 

 monly called red lead (red oxide of mercury). From 

 the statue few would know that. But then Newton, 

 in Trinity Library, is represented (so it has been 

 facetiously put) as making the remarkable discovery 

 that you cannot see through a plastei prism ! 



In this same year Stahl found the gas now called 

 fluorine, and many others were soon studied. 



Cavendish — Watbr, &c. 



Cavendish, who had been studying "nitrous air" 

 and the atmosphere in relation to it, read at the Royal 

 Society in January, 17S4, his celebrated paper, 

 " Experiments on Air," in which he described his 

 experiments that led to the discovery of the com- 

 position of water and of nitric acid. Till oxygen 

 had been discovered as a separate "air" the union 

 of inflammable air (hydrogen) with dephlogisticated 

 air (oxygen) to form water could not, of course, be 

 known ; it was practically a continuation of his 

 previous experiments with H, but he now exploded 

 it in O instead of air. 



We thus see that in the thirty years following 

 (1752) Black's first observations on " fixed air," that 

 H, 0, N, had been discovered as distinct airs or 

 jjasses, that some compounds of C and N were 

 investigated, the composition of water was made 

 known, and the composition of the atmosphere was 

 receiving increased attention. All of these studies lay 

 at the commencement of our modern chemistry. 



Dalton's Atomic Theory. 



Activity in chemical research had been by this 

 time aroused in several centres of civilisation in 

 Europe, and many experiments were made. Guyton 

 de Morveau, in 1782,t wrote an essay on a new 

 nomenclature to represent the then state of the 

 science, but the next great step in advance was 

 Dalton's question. What do all these facts mean? 



Dalton (b. 1766) had from 1796 given considerable 

 attention to the constitution of the atmosphere when 

 in 1802 he communicated to the Manchester Society 

 a paper, " An Experimental Inquiry into the Pro- 

 portion of the several Gases or ' elastic fluids ' Con- 

 stituting the Atmosphere." It is worth noticing his 

 analysis, as it is an illustration of the way in which 

 analyses were in his time given in percentages : — 



Azotic gas 

 Oxygenous gas ... 

 Aqueous vapour... 

 Carbonic acid gad 



75-55 by weight. 



23-32 ,. „ 

 1-03 ,. ., 

 010 ,. ,. 



10000 



A great many chemists set about examining the 

 constitution of the atmosphere, with different results. 

 We now know that it is only the azotic gas (nitro- 

 gen) and the oxygenous gas (oxygen) that have a 

 constant proportion, while the carbonic acid gas and 

 the aqueous vapour and other constituents vary ac- 

 cording to circumstances. 



Dalton's paper, however, has a higher interest. 

 In it he mentions that he found that 100 measures 

 bv weight of common air would combine in a narrow 

 tube with 36 measures of pure nitrous gas or with 

 72 in a wide vessel— 72 is the multiple of 36. The 

 combination would take place in no intermediate 

 quantity. He subsequently examined the gases 

 known as light carburetted hydrogen and heavy rir- 

 buretted hydrogen, and here he found the carbon in 

 the latter double tnat of the former. This set him 

 thinking about the proportions by weight in which 



* Phil. Trans., lxv.. p. 357. 



t Observations dt Physique, 1732. May. p. 371. 



combinations take place, and he enunciated the view 

 that they all do so in some definite proportion or 

 some multiple of that proportion. This, which is 

 now known as the law of chemical combination in 

 multiple proportion by weight, has been so definitely 

 established by countless experiments, that it forms the 

 foundation of all chemical work. (One illustration 

 may make the law clear. There are five distinct 

 compounds of N and O known, and the proportions 

 by weight of O in them are 16, 32, 48, 64, 80, to 28 

 of N in each case.) A year later he read another 

 paper in which he stated what he conceived to be 

 the explanation of these facts. The paper was 

 entitled " On the Absorption of Gases by Water." In 

 it he asks the question, Why does not water admit its 

 bulk of every kind of gas alike ? — and his reply is, " I 

 am nearly persuaded that the circumstance depends 

 on the weight and number of the ultimate particles 

 of the several gases. . . . An enquiry into 

 the relative weight of the ultimate particles of 

 bodies is, as far as I know, entirely new." This 

 guess or theory he proceeded to work out, 

 and in \*Or> published his first paper " On the 

 Weight of the Atoms of Different Bodies." 

 This theory to account for the law is quite apart 

 from the law itself. The law is an established fact. 

 The theory may possibly even yet turn out to be not 

 the fully true one. Gay-Lussac's paper of 1809.* 

 " On the Combination of Gases by Volume." lor a 

 while caused some confusion, especially to Dalton 

 himself. Gay-Lussac showed that gases combine 

 with one another by volume in proportion of 1 to 1, 

 1 to 2. 1 to 3, &c, but no intermediate volume. A 

 study of the question, which it would take too 

 long to enter into, showed that the two lines of 

 research were confirmatory, and not antagonistic. 

 Dalton's theory is known as the " atomic theory." 

 The Swedish chemist, Berzelius (who, following 

 Richter. was working at the same subject), brought 

 out in 1812 his paper " On the Fixed Proportions 

 and Weight of Atoms," based on exact and manifold 

 experiments. 



Whatever may be the future of the atomic theory, 

 it is accepted as at least " a good working hypothe- 

 sis." Repeated experiments, with instruments of 

 delicate precision have been made since Dalton's 

 time. On the theory or assumption that the rela- 

 tive combining weights of different " bodies " (as 

 Dalton called them) indicates in all known com- 

 binations the relative weights of their atoms we 

 have our tables of atomic weights of the elements. 

 W, S. .V. 



(To be continued.) 



HARDY 



FLOWERS 

 HOLLAND. 



FROM 



Mb. C. G. van Tcbergen, jun., of Swannenburg, 

 Haarlem, has sent another collection of Lilies and 

 hardy flowers from his nursery, amongst them a 

 handsome spike of L. Hansoni. This species has 

 proved itself to be a better garden plant than it was 

 thought to be at first. It was at one time con- 

 founded with L. avenaceum, and when exhibited for 

 the first time at South Kensington it was awarded 

 a Second-class Certificate. Later — on June 18, 1878 

 — a fine pot of it was exhibited by Mr. G. F. Wilson 

 for a second time before the Floral Committee, when 

 it received a First-class Certificate. It has since 

 proved to be an excellent garden plant, well deserv- 

 ing the highest award ; in fact, the gravest objection 

 to Second-class Certificates is contained in the fact 

 that perfectly new plants are seldom shown at their ■ 

 best the first time, and a first-class thing may be 

 depreciated in value for lack of sufficient material 

 to show its intrinsic worth. The lovely Chionodoxa 

 Lucilise. for instance, was passed over the first time, 

 and received a First-class award when ample 

 material was available. 



L. pardalinum. with stems 8 feet high and seven 

 flowers on each, is a noble Lily. We have it in nur 

 own flower borders, but it has never exceeded 6 feet ; 



s les una 



probably our soil is too dry for it, as it seems to be 

 a moisture loving plant. Dr. Bolander, who saw it 

 growing in its native haunts in California, describes 

 it as a magnificent Lily, attaining a height of from 

 6 to 9 feet, at an altitude of about 4000 feet, and 

 growing in wet, boggy soil. The petals are yellow, 

 densely spotted with purple red dots ; the tips of the 

 petals are orange-red, and unspotted. L. pardalinnm 

 angustifolium is also sent ; it is richer in colour, 

 the petals as well as the leaves being longer and 

 narrower. L. Parry i came to hand in capital con- 

 dition, and grows freely over there. Its clear yellow 

 flowers, lightly spotted, are exceedingly pretty. As 

 a choice border plant, it takes high rank amongst 

 Lilies. It is from the same altitude in California as 

 L. pardalinum, and was discovered " in the Potato 

 patch of a settler in boggy soil." 



A vigorous spike of L. Martagon dalmaticum 

 shows what an excellent border plant it is ; the 

 flowers deep purple, faintly spotted. The good old 

 L. chalcedonicnm is also amongst them. Its 

 native habitat is Hungary, and always on the tops of 

 the mountains. 



A spike of L. excelsnm was sent to show the vigour 

 of this species, the buds were unopened ; but these 

 open when the spike is placed in water. This 

 has been grown in England on spikes 6 feet high, 

 and twenty-four flowers on a spike. 



L. philadelphicum, an interesting and distinct 

 species, is well known, and was first grown by Mr. 

 Philip Miller in 1757. The flowers are orange-red, 

 with blackish red spots. Miller considered this and L. 

 Catesban to be " less hardy than some of the other 

 sorts." 



L. Krameri. — This fine species, or hybrid, wss also 

 sent — a deeply coloured form of it. Mr. Baker be- 

 lieves it to be a hybrid between L. speciosum and L. 

 japonicum ; but whatever it is, it is a beautiful 

 Lily, and succeeds well in the open border. I was 

 talking about this Lily to Mr. G. F. Wilson the 

 other dav, and he says it has been grown with as 

 many as nine flowers on one stem with Mr. Mcintosh, 

 at Duneevan. One, two, and three flowers on a 

 stem are more frequent. This has large delicate 

 pink flowers. This andL. auratum thrive admirably 

 in the soil of Rhododendron beds. 



Four more distinct forms of L. Thunbergianum 

 show how this useful old species varies not only in 

 the colour, but also in the form of the flowers. By 

 far the best is a new form introduced from Japan, 

 and unnamed. The flowers are well formed, and of 

 a decided scarlet, shade. 



Pictum is a free-flowering vigorous variety, with 

 reddish-orange coloured flowers ; sanguineum is 

 dark coloured, but the form of the flower itself is 

 not good. The darkest variety is grandiflorum, but 

 it is a misnomer, as the flowers are not large nor of 

 good form. The variety grown in England has 

 orange-yellow flowers of good substance. Mr. 

 Tubergen's variety corresponds with our atro-san- 

 guineum. 



The silvery variegated form of L. longiflorum is 

 a pretty plant for borders or pot culture. A long 

 healthy spray of Littonia modesta Keitii is also sent 

 with the note, " Darker in colour and more numerous 

 flowers than L. modesta. Against a very warm and 

 sunny wall a lovely thing ! " 



The flowers are orange-yellow, and one is pro- 

 duced at the axil of each leaf. It forms a curious 

 tuber as large as a Spanish Chestnut. Tricyrtis 

 macropoda is a novel plant for the herbaceons border. 

 It is probably a better garden plant than T. hirta, 

 which flowers too late in the autumn to do any good. 

 It has creamy flowers densely spotted. 



A handful of Brodisea grandiflora shows most 

 vigorous development. It was named in honour of 

 Mr. J. Brodie.of Brodie, in North Britain. Douglas 

 collected it for the Royal Horticultural Society in 

 dry plains west of the Rocky Mountains, and it 

 blossomed in the gardens of the Society in July. 

 1 338, in the open border in peat soil. 



A bunch of Ixia Galatea represents the best of the 

 late flowering varieties. It has well formed pure 

 white flowers with a black centre. 



A few specimens of a bulbous plant with yellow 



