CHEMICAL SCIENCE. 253 



oils, tar, grease, etc., from any variety of fabric, from leather, wool, lor the 

 cleaning of gloves, etc. For the above articles the benzole is employed by 

 simple rubbing, and through its great volatility no mark or permanent odor 

 remains on the substances treated. Mr. Calvert also applies benzole for the 

 extraction of grease, oils, etc., from cotton-waste and rags used in wiping 

 machinery. These substances are first saturated hi a close vessel with the 

 benzole, which is afterward pressed out, and subjected to distillation. The 

 benzole distills over at a low temperature, but the grease and oils dissolved 

 by it remain behind, and can be collected and used. 



PHYSIOLOGICAL AXD THERAPEUTIC EFFECTS OF CAEBOXIC 



ACID. 



Some time since M. Herpin stated the following facts to the French 

 Academy : Dr. Struve took the Marienbad waters for a painful affection of 

 the leg. He had been unable for several weeks to walk without a crutch. 

 Dr. Struve had the notion one day of exposing his leg to the action of the 

 carbonic acid which escapes freely from the spring at Marienbad, and forms 

 a bed several diameters deep over its surface. After exposure for a while it 

 produced a pricking sensation and warmth, which went on increasing till it 

 occasioned a profuse perspiration of the diseased limb. Upon withdrawing 

 his leg, he was surprised to feel no pain, and to find that he was able to 

 walk without his crutch. He continued this treatment for some time, and 

 has since experienced no return of his complaint. There are now in Ger- 

 many special establishments for baths, douches, and the inhalation of carbonic 

 acid. According to M. Herpin, the first effect of exposure to the gas is a 

 sensation of pleasant heat, like that from a garment of fine wool, then a prick- 

 ing, and afterward a burning which has been compared to that from mustard. 



On the occasion of this communication, M. Boussingault related how he 

 happened in 1826 to witness some of the effects mentioned by M. Herpin. 

 He was visiting in the Quindin, New Granada, a part of the Cordillera, some 

 solfataras, where numerous workmen were occupied melting and purifying 

 sulphur. He encountered a crevice, whence issued abundantly a gas of the 

 odor of sulphureted hydrogen. He attempted to descend in it hi order to 

 ascertain the temperature ; but he had hardly entered the crevice when he felt 

 a suffocating heat, which he estimated to be at 40 Centigrade, and a pricking 

 hi the eyes ; respiration being difficult, he ascended quickly ; his face was red, 

 and his perspiration abundant. After a while he descended again with his 

 thermometer, and was surprised to find a temperature of only 19i Centigrade. 

 The extreme temperature was 22 Centigrade. The gas was composed of 95 

 per cent, of carbonic acid, and 5 per cent, of atmospheric air and sulphureted 

 hydrogen. It was hence the carbonic acid which caused the sensation of heat 

 and the irritation of the eyes. At two other times, in 1827 and 1830, 

 M. Boussingault experienced again the same sensations. He observed 

 that the workmen who worked long in the solfataras of the Cordillera, in 

 contact with carbonic acid, experience an enfeebling of the sight, and some 

 of them become blind. Dr. Herpin confirms the fact with regard to the 



