CHEMICAL SCIENCE. 199 



introduced into the fermenting liquid. These facts, together with the 

 experiments as to the action of poison on yeast, seem to admit of no 

 other explanation, even by the ingenious theory of Liebig. Mr. Erni 

 adduced a number of his experiments on other kinds of fermentation, 

 showino- that different kinds of fermentation are due to different kinds 



o 



of fungi. 



Prof. R. E. Rogers remarked, that while he regarded as interesting 

 the fact stated by Mr. Erni, of the power of arsenic to " poison " the 

 yeast fungus, and thus prevent its further development and propaga- 

 tion, and therefore to arrest vinous fermentation, yet he did not think 

 we could from that conclude it to be a poison to all the lower forms 

 of vegetation ; or that, because a substance is a poison to animals 

 (as in the case of arsenic) , it is therefore so to vegetables. He cited 

 the fact, that not only is vegetation freely developed in many saline 

 solutions, but especially often in those of the arsenite of potassa and 

 corrosive sublimate, substances the most poisonous to animal forms, 

 and in ordinary cases remarkable for their antiseptic properties. 



ON A MEANS OF CHECKING DISEASE IN POTATOES. 



DR. A. A. HAYES, of Boston, submitted to the Massachusetts Leg- 

 islative Agricultural Society, in January, a communication in regard 

 to the remedies which may be adopted for the prevention and arrest 

 of the potato disease. He says, " In the course of the experiments 

 undertaken by me, it was noticed that a reduction of temperature by 

 exposure to cold air greatly diminished the rapidity of decay, while 

 a slight increase of temperature hastened it ; moisture being present 

 or not. Heat, in a moist atmosphere, increases the destruction, and 

 samples which had been cooled, and thereby partly protected, readily 

 passed through all the changes when again exposed to warm and 

 humid air. After using several substances, by direct contact with 

 diseased parts of potatoes, I soon found that the mixture of sulphurous 

 acid, nitrogen, and common air, such as exists when sulphur is burnt 

 in close vessels, would prevent the further progress of the disease in 

 tubers already affected, and that when exposed in contact with tubers, 

 passing through all stages of the disease, no further change in the 

 prepared ones was induced. The trials were varied, and the uniform- 

 ity of the results has led me to conclude that the fumes of burning 

 sulphur, flowing in contact with potatoes partly diseased, will arrest 

 the further progress of the disease, and prevent decay. It is proper 

 that this conclusion should be received as an expression of fact, under 

 the circumstances of experiments on a small scale, and with no more 

 than two varieties of potatoes ; but I confidently expect that the im- 

 portance of the application will be seen in the largest exhibition of its 

 effects. 



" The practical use of the sulphurous acid gas is very simple, and 

 not expensive. Crude sulphur, inflamed in a shallow, cast-iron ves- 

 sel, or an earthen pot, furnishes the fumes, which may be led by 

 wooden pipes to the lower parts of bins filled with the roots, until the 

 unoccupied space is filled with them. As the fumes cool, they be- 



