GENEKAL NOTES. I 7 I 



The Souring of Milk during Thunder-storms.*- -In Science of 

 Sept. 19, 1890, appeared a short note on some work recently clone in 

 Italy by Professor Tolomei on the souring of milk during thunder- 

 storms. Professor Tolomei concludes that there is a sufficient amount 

 of ozone generated at such times to coagulate milk by a process of 

 direct oxidation, and a consequent production of lactic acid.t 



Similar results have been obtained by other experimenters, and 

 some have even gone so far as to say that free oxygen, when in 

 contact with milk, will generate enough lactic acid to coagulate its 

 caseine. 



These results are very different from some obtained in this labora- 

 tory. While working on the bacteria in milk the idea occurred to us 

 to find out, if possible, the truth of the somewhat widely accepted 

 theory that milk will sour with extreme rapidity during thunder- 

 storms. Although the statement that this is an oxidising action had 

 been frequently made, a Mr. lies of Baltimore was the first, so far as I 

 know, to perform any experiments in this direction.^ His method 

 was to subject milk to the action of ozone, generated by an electric 

 spark passed through oxygen, above the milk. He found a rapid 

 coagulation produced, which he attributed to the direct oxidising 

 action of the ozone. 



Our method was similar to that of Mr. Iles's. A Wolff bottle 

 was filled about one-third full of milk, and the air in the bottle 

 displaced by pure oxygen. Through the opposite necks wires leading 

 from a Holtz induction machine were passed into the interior, and the 

 necks plugged tightly with cotton to prevent any escape of oxygen ; 

 ozone was then generated by passing a spark across through the 

 oxygen from one pole to the other. In some cases, instead of the 

 spark, a " silent discharge " of electricity from the two poles was used 

 to generate ozone. 



In all cases a second bottle was partially filled with milk, and 

 kept as a "control;" i.e., one in which the milk is left in its normal 

 condition. 



For some of our experiments three bottles were used,- one left 

 as a control ; a second filled with milk and oxygen ; while a third was 

 filled, like the second, with milk and oxygen, and then treated with 

 the electricity. We thus had milk under three conditions: 1. In its 

 normal state ; 2. Under the influence of free oxygen ; 3. Under the 

 influence of free oxygen plus a certain amount of ozone. The elec- 

 tricity, in all cases, was passed through the oxygen for at least half 

 an hour. That a considerable quantity of ozone was generated, was 

 shown by its odor, and strong action on starch-iodine paper. Our 

 results were very different from those given by lies and Tolomei. 

 The milk treated with ozone, or simply pure oxygen, soured a little, 

 but only a little, faster than normal milk. If the milk in the control 

 coagulated in thirty-six hours, the milk experimented on coagulated 

 only an hour or two earlier. 



Science, March, 27th, 1891, p. 178. 

 T A more extended account of Professor Tolomei's experiments is given in Bicder- 

 manri'a Central-Elatt fiir Agriadturchemic, 1890, p. 538. 



X Chemical News, vol. xxxvi. p. 237. 



