IM 



CHEMISTRY. 



ons rays of \ight would correspond to the 

 curve of brightness, has been questioned, ami 

 different correspondences have been 'nhsti- 

 tutcd. Thus, it has been held that this de- 

 composition-curve corresponds with the curve; 

 of heat-intensity, or to the curve of absorption 

 by chlorophyll, and of mechanical intently or 

 heat-action. But experiments made by Dr. 

 Pfeiffer, and communicated to the Marburg 

 Society of Natural Science, confirm Draper's 

 conclusion. In that communication, Dr. 1'feif- 

 fer, in the first place, refutes the conclusions 

 of Lonimel and Waller, who asserted corre- 

 spondence with the chlorophyll curve. Ho 

 snows that chlorophyll solutions may be ob- 

 tained which give the absorption-bands, and 

 yet show no decomposition of carbonic acid, 

 but rather absorb oxygen. Hence it is an un- 

 warranted inference that the rays most active 

 in decomposition are those which are extin- 

 guished. In order to determine experimen- 

 tally the decomposing force of different rays, 

 the author adopted the method of counting 

 the bubbles of gas given off by a branch in 

 water. His procedure, as detailed in the 

 iieal A'eiti, was as follows: 



the tnb* as a thin, peculiarly colored blnish- 

 green-purple coating. The lower stratum is 

 of a bright-red color. Antimony terohloride 

 i, therefore, a very good reagent for the pe- 

 troleum-oils. With oil of turj iiititK- he ob- 

 tained a very violent reaction, attended by the 

 .tion of great heat and the deposition of 

 a yellowish resinous mass. 



Soda- Xonnfatturr. The Proceedings of the 

 German Chemical Society contains a paper by 

 l>r. Rudolph Wagner on the revolution in the 

 process of soda-manufacture, brought about by 

 the introduction of the "Ammonia Process. 

 That distinguished chemist, while acknowledg- 

 ing the immense superiority of the new method 

 over all preceding methods, shows that it pre- 

 sents really nothing new to science, its great 

 merit being that it renders available for eco- 

 nomic nse a principle that has long been rec- 

 ognized. The value of the process is, never- 

 theless, verv great, and there is no doubt at 

 all that it has already effected a revolution in 

 soda-manufacture. The ammonia process, says 

 Dr. Wagner- 

 Is not new, as far as its chemically scientific side 

 is concerned. It belongs to that claaa of methods 

 which for a century past have striven to accomplish 

 the Jinrt conversion of common aalt into soda, no 

 matter whether oxide of lead, bicarbonate of mag- 

 nesia, caustic lime, alumina, silica, sesquioxide of 

 chromium, or hydrnfluosilicic acid, were employed to 

 decompose the chloride of sodium, without having 

 attained any noticeable result. The " new process " 

 is baaed upon the action of bicarbonate of ammonia 

 on a concentrated solution of common aalt, a matter 

 already known for a third of a century', whereby the 

 greater part of the sodium is precipitated as bicarbon- 

 ate of soda, while chloride of ammonia remains in 

 the solutions, from wbleb, by means of caustic lime, 

 ammonia can again be obtained to serve for the de- 

 composition of fresh portions of aalt The carbonic 

 add necessary for the continuance of the process ia 

 In part furnished by the bicarbonate of soda, on 

 liana* mains; it by heat to neutral carbonate ; in part 

 the carbonic acid issuing from natural vents in tho 

 earth ia used, or it la formed by the combustion of 

 coal. 



The advantage* of the new process, the details of 

 which an. as a matter of course, still withheld from 

 publication, over that of Lehlane are self-apparent. 

 They culminate in the possibility of the dirtet con ver- 

 sion of salt into soda, and in the fact that out of satu- 

 rated saline solutions only the sodium is precipitated, 

 and not the other metals of the salts of the mother- 

 liquor, In the absolute freedom of the product from 

 all sulphur compounds, in the high deyrte of the soda 

 Mnafl. in the simplicity of the apparatus and uten- 

 sils. In the mat economy of fuel and labor, and in 

 Ihefcet, which, in the interests of hygiene and the 

 neiftihnrs of the manufactory, must certainly not be 

 nOtly valued, that no noiioua by-products and 



refuse an produced. The weak point In the am- pasteboard cover was applied to ..tie side of the ves- 

 aonh process, at present, ia the loaa of the chlorine sel, having a vertical slit, 18 millimetres in brendth. 

 * *5' l j *hlch by the regeneration of the ammo- opposite the brunch, nnd including it. The vessel 

 laja obtained In worthless chloride of calcium. was then submitted to the spectral rays, which came 



to it at right angles through the slit. Care was 

 taken that, in moving the vessel to a new posi- 

 tion, the rays should still meet its surface at right 

 an tries. 



The counting of bubbles began at the yellow. 

 After each removal, a short time was allowed for 

 the stream of bubbles to become eonstnnt. From 

 the yellow throughout there was in every case a 

 continuous diminution in the number of bubbles, as 

 the following shows : 



Two lenses of different focal distances were so 

 combined that solar rays, passing through tin in 

 from a heliostat, issued nearly parallel, and formed 

 an image of 40 millimetres diameter. The diameter 

 of this image fell on a slit S millimetres broad ; and 

 the rays, then passing through a prism and an achro- 

 matic lens, formed a spectrum at 2 to 24 metres 

 distance, having a length of 280 millimetres, and a 

 height of 60 millimetres. The weakening of tho 

 rays through absorption and reflection was reckoned 

 at'about rS, but the absolute intensity was not meas- 

 ured. The yellow was sufficiently bright to cause 

 pain in looking at it. The spectrum was not pcr- 

 feetly pure, but proved sufficiently so for the pur- 

 pose. 



In the gasomctric method, Dr. Pfciffcr remarks, 

 there are various disadvantages. A long e*| 

 is required, and small errors arc apt to creep in, 

 both in this and in removing the leiives i'mm the 

 tube ; and these errors assume importance, from the 

 small quantity of carbonic acid decomposed. The 

 method of counting gas-bubbles, indeed, does not 

 give a perfectly accurate value for the quantity of 

 ('<>, decomposed ; still, in all circumstances where 

 the bubbles increase, there is more ei,. rpetie ,1. 

 position, and conversely, the amount of oorrespond- 

 encc being sufficient. When a plant is giving off 

 bubbles, the slightest shadow makes a dlftrenee, 

 and in less than a minute the new stream of bubble* 

 becomes constant for the new lipht intensity. 



Tho plant employed was Klvdta Canadttitit. 

 Branches of this, 4.'>' millimetns long, fixed to a 

 glass rod. were placed, with cut surface uppermost, 

 in a parallel-sided glass vessel filled with water. A 



tasxUawth. 



to chemical manufacturers at- 



- . . . : UN DM groat --. 



I capyciallj the effect on the consumption of sul- 

 inr, lh manufacture of sulphuric acid, and the 

 pnw of muriatic acid and chloride of lime, cannot 

 at UM prsnt moment b foreseen. 



Dre**p<l*g Artion tf Light. Dr. John IT. 

 Draper's awrrtlon that the curve which should 

 th decomposing power of the vari- 



