September i6, 1892.] 



SCIENCE. 



157 



soured in forty-six hours, the average length of time in which 

 milk not aerated became acid. It was also shown that skim-milk 

 from aerated milk contained .53 per cent of fat against .31 per 

 cent of fat in skim-milk from milk not aerated ; this milk was set 

 in Cooley cans. 



During April and May of the present year the writer, assisted 

 by Mr. H. C. Beckman, an agricultural student in Purdue Uni- 

 versity, carried on a series of tests to note the influence of aeration 

 upon the securing of butter-fat in milk, the details of which were 

 presented to the Society for the Promotion of Agricultural Science, 

 at Rochester, N.Y., on Aug. 20. Fifty pounds of fresh, warm, 

 mixed milk was divided into two lots of twenty-five pounds each. 

 Lot one was passed over an Evans and Heuling aerator and re- 

 duced in temperature, on an average, from 88.8" to .56.5'= F. This 

 milk was then set in cold water, and skimmed in twenty-four 

 hours. Lot two was treated like lot one, excepting that it was 

 not aerated. Twenty-nine lots of cream were secured from each 

 class, which resulted in a total amount of 183 pounds 51 ounces of 

 cream from aerated milk, and 181 pounds 10* ounces from that 

 not aerated. Daily tests were made with the Babcock machine, 

 which showed an average of 24.4 per cent fat in cream from 

 aerated, and 34.0 per cent of fat in cream from non-aerated 

 milk. Thirty-two pounds seven ounces of butter were made 

 from the cream from aerated milk, and six ounces less from the 

 non-aerated. 



The limited amount of experimental evidence published would 

 indicate that aerated milk kept sweet somewhat longer than that 

 not so treated, other things being equal. Our practical observa- 

 tions seemed to point this way. In order to more carefully in- 

 vestigate this point, a chemical investigation of the subject was 

 carried on under the direction of Professor H. A. Huston, chemist 

 of the Purdue University Agricultural Experiment Station. The 

 milks were treated as noted above, one lot being aerated and the 

 other not. Check samples from each lot were taken every twelve 

 hours. The relative acidity of the milks was determined by 

 means of the quantity of one-half normal caustic potash required 

 to produce a neutral tint. On account of the well-known amphe- 

 genic action of milk with litmus paper, it was considered desira- 

 ble to obtain results with more than one indicator. After repeated 

 trials with a large number of indicators, phenol-phtbalein and 

 corralline were selected. The milk was titrated at once after 

 sampling. After the first twelve hours 5 cubic centimeters one- 

 half normal HCl were added to 250 cubic centimeters of the milk ; 

 25 cubic centimeters of this milk were taken for titration. Sev- 

 eral methods of setting the lots of milk were tried. A synopsis 

 of these tests, over equal periods of time, shows the following in- 

 teresting results : In sixteen tests the aerated milk was most acid ; 

 in eleven tests the non-aerated milk was most acid ; while in seven 

 cases the acidity was equal in both lots. These tests, which 

 represent considerable painstaking work, do not indicate the re- 

 sults from aeration that were to have been expected as based on 

 current opinion. 



If cows are properly fed and milked, the writer does not believe 

 that normal milk will be disagreeable if set in clean vessels in 

 sweet surroundings, yet there are those who lay great stress upon 

 the animal odor in milk, and the necessity of removing it. It is 

 claimed that the aerator will accomplish this. In the Wisconsin 

 Farmer of Sept. 3, a short article is published on aerating milk, 

 credited to " a Vermont authority." Says the writer, " by 

 aerating milk, odors can be completely driven out that have been 

 absorbed by the milk after being di-awn from the cow. Odors 

 that were derived by the milk through the system of the cow are 

 not so easily taken out. They will be somewhat lessened, but 

 can never be wholly removed. Milk should be aerated as soon as 

 possible after it is drawn, and it should, at the same time, be 

 cooled. Aerating alone is an advantage, but its good effects en 

 the keeping of milk are much increased by bringing the milk 

 down to 55° or lower. Milk should keep at least twelve hours 

 longer for the aerating. By using a cooler and aerator faithfully 

 it is possible to dispense with ice in selling milk under the ordinary 

 conditions as they occur in the smaller cities; but where the milk 

 is to be brought by train, and is 24 to 36 hours old before it is put 

 on the milk cart, it would be necessary to use ice even with 



aerated milk. . . . The man who is raising his cream by shallow 

 setting or cold deep setting has no use for a milk aerator or a 

 milk cooler. Either would be a positive detriment, occasioning 

 the loss of a large amount of butter in the skim-milk." 



This subject is one of considerable interest and importance. A 

 person has no business to have milk so contaminated by odors 

 after being drawn, as to require the use of aeration to make it 

 palatable. As bearing on the other points in the article quoted, 

 I believe there is but little experimental evidence at hand, though 

 this in a measure substantiates it. Our experiment stations have 

 an opportunity to do some interesting work in this direction. 



Purdue University Agricultural Experiment Station, Lafayette, Indiana. 



REPORT OF THE SUMMER SCHOOL OF THE BROOKLYN 

 INSTITUTE FOR THE SEASON JUST CLOSED. 



BY HERBERT W. CONN, DIRECTOR. 



The Biological Laboratory of the Brooklyn Institute of Arts and 

 Sciences has just closed its third season of biological work. The 

 session has been the most successful one in its history, and as a 

 preliminary report of the summer's work it will be fitting to give 

 a brief account of the history of the Laboratory, together with its 

 purposes and aims, in order that those interested in the matter 

 may gain a better knowledge of the school. 



The Biological Laboratory at Cold Spring Harbor was organized 

 in 1890. It owed its inception to the Brooklyn Institute, and has 

 been established as a branch of that institution of popular educa- 

 tion. The foundation of the school was made possible through 

 the generosity of Mr. John D. Jones and the New York Fish Com- 

 mission. Mr. Jones at the outset contributed a considerable sum 

 of money towards purchasing the equipment of the Laboratory, 

 and the New York Fish Commission offered to the school the use 

 of its buildings and appurtenances located at Cold Spring Harbor, 

 L I. Other friends, among whom may be mentioned Mr. Eugene 

 Gr. Blackford, Professor Franklin W. Hooper, Dr. Oliver L. Jones, 

 Mr. Louis O. Tiffany, Mrs. H. G. DeForrest, and Miss Julia B. 

 DeForrest, have contributed generously toward the equipment 

 and support of the school. By means of these contributions and 

 from students' fees the Laboratory has been thus far supported. 

 Up to the present time the hatchery of the New York Fish Com- 

 mission has served as a laboratory building, but the school has 

 reached the limit of the accommodations thus offered, and is 

 hoping to erect a special laboratory building during the coming 

 year, which will be especially adapted to biological work. The 

 Laboratory has been supplied with a launch, collecting apparatus, 

 aquaria, and other appliances necessary for the pursuit of biologi- 

 cal work. A library of biological literature has been furnished, 

 and microscopes, etc.. have been loaned by the Brooklyn Institute 

 and Wesleyan University. During the present year a beautiful 

 lecture-room has been fitted up for the school by the Wauwepec 

 Society, a society organized by Mr. John D. Jones for local im- 

 provement at Cold Spring Harbor. The New York Fish Commis- 

 sion has given the use of its boats, aquaria, pumps, and other 

 apparatus, which has been of great value to the school. Thus 

 equipped, the school has been enabled to enjoy three successful 

 seasons, and to demonstrate the need of further support and better 

 equipment. The Wauwepec Society is contemplating the erection 

 of a laboratory building for its use, and its further growth is only 

 a matter of time. 



During its three years of existence, over sixty persons have 

 made use of the advantages offered by the Laboratory, either in 

 study or in investigation. Those attending the Laboratory have 

 included college professors, public-school teachers, physicians, and 

 students of various grades of schools. 



The Laboratory was, for the first year, under the direction of 

 Bashford Dean, Ph.D., of Columbia College. During the last 

 two years it has been directed by Professor Herbert W. Conn, 

 Ph.D., of Wesleyan University, who has been assisted by Professor 

 Charles W. Hargitt, Ph.D., of Syracuse University, and Professor 

 H. L. Osborn, of Hamline University. In addition to these, there 

 have been at the school leading biologists from various institutions, 

 including Columbia College, Rutgers College, Trinity College, 



