180 Alfred J. Etvart .- 



after dissolving it in hot alcohol, the total weight of residue wa» 

 0.21 gram, i.e., a slight loss instead of a gain. 



In the experiments mentioned in the previous paper in which 

 chlorophyll films appeared to gain in weight after exposure to 

 light in water saturated with carbon dioxide, the films were 

 weighed in situ in the tube after pouring oft' the water and drying 

 in a current of rarified dry air at room temperature. Repeating 

 a similar experiment, a film weighing 0.105 gram appeared to in- 

 crease in weight to 0.228 gram. Close observation showed, how- 

 ever, that dry chlorophyll films in w^ater swell and imbibe water, 

 and that this water is not removed wholly by drying at room tem- 

 perature, the films assuming an approximately constant weight 

 while still containing a large percentage of water. The same film 

 on dissolving in alcohol and petrol ether weighed on drying 0.102 

 gram. 



On the other hand, if dried in air at 50°C. or 60°C., the films 

 lose weight by oxidation. In one test experiment this loss 

 amounted to 3% in ten hours. In a second experiment a dry film 

 weighing 0.264 gram, weighed 0.251 gram after sixteen hours at 

 60° in air and darkness, and 0.234 gram after forty hours, being- 

 then quite yellow with nearly all the green colour lost. This error 

 can be avoided by drying in vacuo, or in hydrogen or nitrogen. In 

 a further experiment conducted with every possible precaution, a 

 chlorophyll film weighing 0.228 gram after one week's exposure to 

 light in water saturated with carbon dioxide weighed 0.223 gram, 

 i.e., it lost slightly instead of gaining in weight. 



The film is, however, not wholly insoluble, but a little matter 

 passes into solution in the water, and this may include one product, 

 formaldehyde, which is mostly lost on evaporation. 



Experiments on a large scale were then carried out by using 

 ordinary sparklet syphons. Dry chlorophyll, obtained by i^etrol 

 ether separation from an acetone extract and subsequent purifica- 

 tion, was weighed in a small beaker, dissolved in a little ether,, 

 poured into the syphon, and the beaker then dried and reweighed. 

 A current of warm air was passed through the syphon, which was 

 inclined and revolved until an even chlorophyll film formed up to 

 the danger mark. The syphon was then filled to this level with cold 

 boiled w^ater, the head screwed on a sparklet bulb attached, and 

 after previous exhaustion by a Geryck pump while in the inverted 

 position, the bulb was pierced, and the water charged highly 

 with carbon dioxide. One syphon was exposed to sunlight for a 

 week, the other left in darkness. Owing to the sunlight warming- 



