NOVEMBEB 13, 1908] 



SCIENCE 



669 



generator, installed in duplicate, and con- 

 structed upon such unusually large dimen- 

 sions that each apparatus will supply two 

 himdred and fifty outlets operating simul- 

 taneously, has been adopted. In this con- 

 nection the opinion is advanced that the 

 setting aside of a special room where stu- 

 dents congregate from all over the building 

 for the use of hydrogen sulphide is un- 

 necessary, and inviting the degeneration of 

 liberty into license. In other words, the 

 "stink room," for large laboratories at 

 least, is a relic of the past. A shelf placed 

 out of doors, in a court, for example, may 

 be provided for the limited number of stu- 

 dents, who from time to time must use 

 large quantities of such gases as chlorine. 



Lead-lined iron pipe is used for the 

 transporting of hydrogen sulphide and 

 hard rubber cocks are attached to this on 

 the interior of the hoods. No hydrogen 

 sulphide outlets are had except in the 

 hoods. The front windows of the hoods 

 are suspended upon paraiBned window 

 cord, which I think is superior to the bronze 

 tape or chains used in some laboratories. 



All outlets, except those mentioned, are 

 brought to the front and underneath the 

 floor of the hood. Just within the line of 

 the base of the window-case are bored holes 

 through which the tubing can be led into 

 the hoods. When the tubing is not in all 

 of these holes, the hood is thoroughly ven- 

 tilated, when closed, by means of these 

 openings. 



DISTILLED WATEE 



The problem of economically providing 

 ample distilled water for a large laboratory 

 is one requiring most careful consideration. 

 It has long been known that condensed 

 boiler steam, even with oil arresters, fails 

 to be pure enough even for ordinary labo- 

 ratory work. After securing much advice, 

 the system here oiitlined was adopted. It 

 may be constructed of any number of units. 



The water is preheated to remove free 

 ammonia. We have the evaporators in 

 duplicate and twenty condensers. On the 

 try-out, three hundred gallons were pro- 

 duced in an hour. The apparatus is 

 erected in the attic. The principle upon 

 which it depends is that of boiling water 

 with high-pressure steam passing through 

 coils within the evaporators. The evap- 

 orators are thirty-nine inches in height and 

 thirty inches in diameter, outside measure- 

 ment, and contain one hundred and forty 

 feet of extra heavy drawn copper tubing, 

 properly coiled and coated with the best 

 quality of block tin. The outer shell is of 

 fifty-ounce cold-rolled copper; the heads 

 are of same weight and are securely fast- 

 ened to the sides with three-eighth-inch 

 steel machine bolts. All spuds, nipples 

 and fittings and all inside surfaces coming 

 in contact in any way with the water, are 

 heavily coated with the best qualitj' of pure 

 block tin; all joints are of invisible silver 

 brazings, and all the fittings were sweated 

 and brazed. 



The evaporators are fitted with water 

 gauges and cocks, all necessary steam, 

 water and sewer connections, and suitable 

 hand-holes for cleaning. The condensers 

 are six feet in height, composed of two 

 cylinders, the inner cylinder being seven 

 inches in diameter, and the outer cylinder 

 eight inches in diameter. The inside tubes 

 are constructed of twenty-ounce cold-rolled 

 copper, and the outer tubes of twenty-four- 

 ounee cold-rolled copper, block tin coated 

 inside and out, lap seamed. All joints 

 were sweated and soldered with pure block 

 tin. All fittings for water and steam con- 

 nections are tacked together at regular in- 

 tervals to prevent buckling with brass 

 blocks, block tin coated. The bottoms of 

 the condensers rest upon and empty direct- 

 ly into a large tin-lined reservoir. Tin- 

 lined iron pipes with tin-lined valves serve 



