June 22, 1906.] 



SCIENCE. 



941 



Interesting as these fossils are from many- 

 points of view, they are disappointing in 

 that they throw little light upon the prob- 

 lems- of faunal origins and migrations in 

 the southern hemisphere. 



The Use of Dilute Solutions of Sulphuric 



Acid as a Fungicide: Professor Henry 



Kraemek, of Philadelphia. 



It is stated by Bloxam that finely divided 

 sulphur is gradually oxidized and converted 

 into sulphuric acid when exposed to moist 

 air. It is well known that sublimed sul- 

 phur contains a certain amount of sul- 

 phuric acid. Not only is this true, but it 

 is claimed that if the sublimed sulphur be 

 not dried after washing it to free it of acid, 

 sulphuric acid is again formed. Further- 

 more, it has been pointed out by Polacci 

 that sulphur when mixed with the soil is 

 changed directly into sulphuric acid. 



As a fungicide and insecticide, sulphur 

 is applied directly in the powdered form, 

 or it is applied in the form of a paste to 

 the heating pipes in greenhouses, or it is 

 gently heated on a sand bath, when it is 

 sublimed and distributed over the plants 

 in a finely divided state. 



The fact that sulphur is used in the 

 several ways indicated led to the question 

 as to whether sulphuric acid is not pro- 

 duced under these conditions and as to 

 whether it is not the active agent, destroy- 

 ing the fung-us but not injuring the host. 



Experiments were first cairried on to 

 determine what compounds are formed 

 when sulphur is slowly heated. An appa- 

 ratus was constructed for heating the sul- 

 phur and collecting the gases formed, and 

 it was found that when sulphur is slowly 

 vaporized with access of air that as much 

 as fifteen per cent, of the vaporized sul- 

 phur may be converted immediately into 

 sulphuric acid, little or no sulphurous acid 

 resulting. 



It being thus pretty well established that 



sulphuric acid is formed under the condi- 

 tions in which sulphur is used in green- 

 houses, another series of experiments was 

 carried on to determine the strength of 

 solution which would not be toxic to the 

 host plant. It was found that practically 

 under all conditions, including variation in 

 temperature and susceptibility of different 

 plants to the action of the acid, a solution 

 containing approximately one part of sul- 

 phuric acid to 1,000 parts of water could 

 be used as a spray without any injury to 

 the plants. The solution is best applied 

 late in the afternoon after first sprinkling 

 the plants with water. 



The efficiency of dilute sulphuric acid 

 as a fungicide has been shown by applying 

 it to roses which were badly affected with 

 mildew. Plants growing outdoors as well 

 as in the greenhouse have been treated suc- 

 cessfully. The roses were uninjured by 

 the acid solution and they immediately be- 

 gan to develop new leaves and young 

 shoots entirely free from mildew after 

 three to six applications on alternate days. 

 The acid solution seems to exert a beneficial 

 action on the plants apart from the fungi- 

 cidal action. 



Should subsequent experiments confirm 

 these observations, the use of sulphuric 

 acid will have certain advantages over the 

 use of sulphur, as it does not discolor the 

 foliage as sulphur does, its employment is 

 more easily controlled, and it does not have 

 the odor of the other compounds associated 

 with sulphur. , 



Franklin and the Germans: Professor M. 



D. Learned, of Philadelphia. 



While Franklin's importance as a cul- 

 tural mediator between the German and 

 English colonists in America has never 

 been clearly recognized by the English, the 

 Germans have given the highest praise to 

 his services and perpetuated his name, 

 rather than that of their most cherished 



