752 



SCIENCE. 



[X. S. Vol. XXI. Xo. 541. 



boiling-points of the various samples listed; 

 a comparison of the two will, therefore, indi- 

 cate the probable purity of the different sam- 

 ples. It is obvious that such a card properly 

 filled out will give the instructor at a glance 

 all the information desired concerning his 

 stock. 



I think that I hear the reader saying to 

 himself, ' All very pretty ! but it must take an 

 immense amount of time to get up such a list, 

 and it would be perfectly hopeless to attempt 

 to keep it up to date ! ' It is quite true that 

 it does take some time to prepare such a list, 

 particularly where the mass of material is 

 great, but the time thus lost is very quickly 

 made up by the time saved in the use of the 

 index, and when once done it does not have 

 to be done over again. I assume that every 

 laboratory finds it desirable to take a complete 

 account of stock at least once a year. As to 

 the other objection- — keeping such a list up to 

 date, our method is as follows: Two sets of 

 printed blanks are used, about 3" x 5", one 

 printed on blue paper, the other on white. 

 One is for stock removed, the other for new 

 stock. On the blanks headed ' Removed ' 

 are the following items — substance, amount, 

 maker, location, date, for; on the 'New 

 Stock ' blanks — substance, amount, maker, 

 cost, location, date. Whenever any chemical 

 is removed from stock for use in a research, 

 to replenish a reagent bottle, or for whatever 

 purpose, one of these ' Removed ' blanks is 

 filled out and put on file, and once a month 

 or so these blanks are checked up and the 

 index corrected accordingly. After correct- 

 ing the index, the blanks are not destroyed, 

 but are kept on permanent file, and at the 

 close of the year an examination of the total 

 blanks on file will show exactly how much and 

 where the stock is most in need of replenish- 

 ing, thereby furnishing the necessary informa- 

 tion for the preparation of the annual import 

 order. The ' New Stock ' blanks should also 

 be placed on permanent file after having been 

 entered in the index. It will be found more 

 convenient, in both cases, to use a separate 

 blank for each separate bottle. 



Such a general stock list is not only a per- 

 petual inventory, but it may also do duty as a 



chemical museum catalogue, and be useful in 

 other directions also. For example, it will 

 show instantly any change in the market price 

 of the chemicals listed, and perhaps thus lead 

 occasionally to the correction of unintentional 

 overcharges on the part of dealers. When 

 once made, it requires only occasional atten- 

 tion, and the addition of new cards for new 

 substances. Wherever possible, as in the 

 chemical museum and general stock rooms, 

 the stock should be arranged in the same order 

 as in the index. 



As the above method has appeared to in- 

 terest so many of our brother chemists both 

 here and abroad, I have taken this opportunity 

 of making it available to all, in the hope that 

 others may fimd in it something useful or sug- 

 gestive. It has been in use in the department 

 of organic chemistry of Columbia University 

 for several years, and has been of very great 

 assistance to us in our work. 



Marstox Taylor Bogert. 

 Ha\'emeyee Laboratories, 

 Columbia University, 

 March 30, 1905. 



A QUANTITATIVE CIRCULATION SCHEME. 



The artificial scheme (Fig. 1) to illustrate 

 the mechanics of the circulation in the highest 

 vertebrates consists of a pump, a system of 

 elastic tubes and a peripheral resistance. The 

 inlet and the outlet tubes of the pump are 

 furnished with valves that permit a flow in 

 one direction only. The peripheral resistance 

 is the friction which the liquid undergoes in 

 flowing through the minute channels of a 

 piece of bamboo. To this must be added the 

 slighter resistance due to friction in the rub- 

 ber and glass tubes. 



In this system the pump represents the left 

 ventricle; the valves in the inlet and outlet 

 tubes, the mitral and aortic valves, respect- 

 ively; the resistance of the channels in the 

 bamboo, the resistance of the small arteries 

 and capillaries. The tubes between the pump 

 and the resistance are the arteries; those on 

 the distal side of the resistance are the veins. 

 The side branch substitutes a wide channel 

 for the narrow ones, and thus is equivalent to 

 a dilatation of the vessels. 



