294 ANNUAL OP SCIENTIFIC DISCOVERY. 



statement advanced by Chatin that an appreciable amount of iodine was 

 present in the atmosphere could be admitted. The author had found a trace 

 of iodine in 100 gallons of the water used for domestic purposes in Edin- 

 burgh, as also in about 60 land plants, some of which were edible, such 

 as potatoes, .wheat, barley, oats, beans, peas, pears, apples, and gooseberries. 

 The presence of iodine in the food of animals necessitated its introduction 

 into the system of the animal, and, for a time at least, its retention there. 

 The author accordingly found iodine in the cat, the dog, the pig, the cow, 

 the horse, and man. In every instance but one, muscle was the only part 

 of the animal frame employed. In the horse, however, the lungs, liver, 

 heart, spleen, and kidneys, as well as the muscle, were examined, and 

 each organ yielded iodine. The milk and blood of the cow and common 

 eggs gave a like affirmative result. The passage of iodine from the animal 

 system had also occupied the attention of the author. By wearing a 

 starched gauze respirator for six nights, (about 50 hours,) it was apparent, 

 from no blue or rose tint being imparted to the gauze, that no iodine had 

 left the system by that road ; whilst other experiments showed that the 

 iodine compounds accompanied the other saline matters in their passage 

 from the animal. No direct experiments had been made on soils ; but 

 considering that iodine is uniformly a constituent of limestone rocks, and 

 . .'iat these are always present in and applied to soils, the author believed 

 that the latter must, to a greater or less extent, contain iodine. 



APPLICATION OF ESSENCE OF COAL AS A SUBSTITUTE FOR OIL 



OF TURPENfflNE. 



M. Pelouze, the son of the distinguished chemist of that name, proposes 

 to use an oily fluid consisting of a mixture of carbo-hydrogens, especially 

 ^.of benzoine, &c., as a substitute for oil of turpentine in painting. He 

 obtains this fluid, which boils from 100 to 168 centigrade, by the distil- 

 lation of cannel coal, by means of sur-heated steam. This liquid is color- 

 less, very fluid, and completely volatile, leaving no stain upon paper, and 

 is not altered by exposure to the light. It has a penetrating smell, which 

 reminds one of common coal gas ; but this entirely disappears when it 

 has evaporated. A number of comparative experiments have been made, 

 with the object of comparing it with oil of turpentine, by a committee of 

 the Socicte d'Encouragement of Paris, all of which have resulted in 

 showing that walls, woodwork, &c., painted with the essence of coal, 

 dried far more rapidly, and the smell disappeared sooner, then where es- 

 sence of turpentine was employed. For example, in one case where the 

 coal essence and oil of turpentine were respectively mixed with three 

 times their volume of oil, and employed under exactly similar circum- 

 stances, the smell of the essence of coal was completely dissipated at the end 

 of three days, while that part painted with the turpentine mixture had 

 still a strong smell, and was not completely dry. The introduction of 



