408 



SCIENCE 



[N. S. Vol. XXXIV. No. 874 



this source of air supply leaves mucli to be de- 

 sired on the score of quality. Much street 

 dust may enter the cold air box and be distri- 

 buted throughout the house. And few realize 

 the parching quality of the air in furnace 

 heated houses. I have found the air in a 

 house heated by a good furnace in moderately 

 freezing winter weather in Massachusetts 

 with a relative humidity as low as 16 per 

 cent. This, too, was with the water reservoir 

 of the furnace well filled. Such air is far 

 dryer than that of an oasis of the Sahara in 

 the driest season of the year and it irritates 

 the skin and mucous membrane and carries 

 off moisture so rapidly in insensible perspira- 

 tion as to make it necessary to maintain the 

 room temperature at a point several degrees 

 higher than would otherwise be demanded. 



Furnace heating may be made to furnish 

 much better air for breathing by straining the 

 air, either by means of a thin layer of cotton 

 batting at the entrance of the cold air box or 

 by a layer of the silk-like glass fiber, used for 

 jacketing steam pipes and so on, under each 

 register. The humidity may be considerably 

 increased by supplying boiling water to the 

 evaporating reservoir in the furnace. In 

 single rooms it may be raised by keeping a 

 large coarse towel, frequently wrung out, hung 

 from any convenient support immediately 

 over the register. Where there is a combina- 

 tion of steam and furnace heating, the hot 

 air may be moistened to any desired extent 

 by letting a very minute steam jet enter the 

 heated air inside the outer jacket of the fur- 

 nace. 



Whatever the nature of the heating appa- 

 ratus employed, the householder of inquiring 

 mind will find a good deal of food for reflec- 

 tion in the results obtained by burning touch- 

 paper just over the registers or radiators 

 which serve as the source of heat and watch- 

 ing the distribution of the heated air and by 

 measuring the relative humidity of the air in 

 some living rooms in cold weather, by means 

 of a sling psychrometer. The values corre- 

 sponding to the readings of the wet bulb and 

 dry bulb thermometer can be obtained by in- 



spection of the " Psychrometrical Tables " 

 published by the U. S. Department of Agri- 

 culture, Weather Bureau. 



J. T. Bergen 

 Cambeidge, Mass. 



elementary text-books in chemistry 

 To THE Editor of Science : Professor Miller 

 in his address given at Indianapolis and pub- 

 lished in No. 8Y0 of Science criticizes in some 

 important particulars the current elementary 

 text-books in chemistry. Personally I would 

 have been better pleased with the excellent 

 and timely address if he had said " many 

 text-books," or " most text-books," instead of 

 " our text-books." It should also be said that 

 an elementary book ought rather to be con- 

 servative than radical, as long as the conserv- 

 ative position has a considerable following 

 among leading chemists. 



The particular criticisms offered by Pro- 

 fessor Miller suggest the general subject and 

 lead me to speak of one or two others, which 

 I confess do not apply to all elementary texts. 

 Passing by criticisms that are often made — as 

 that many books are too learned and heavy in 

 style, that they make too much of chemical 

 theory and do not show respect enough for 

 chemical fact, etc. — I want to say a word con- 

 cerning the immense field that the usual book 

 presents to the high school student, to be com- 

 pleted in one year. I do not refer to the size 

 of the book but the amount of matter. Some 

 of the smaller books sin worst in this regard, 

 being little more than a synopsis of a good 

 college book. I know how much can be said 

 in favor of a complete view of an important 

 subject of study, and how much about the 

 vital character of any particular suggested 

 omission, but there is one sort of reduction 

 that might easily be secured. This large field 

 has grovm of recent years partly by annexing 

 outlying territory that was formerly regarded 

 as belonging to other subjects of study. Many 

 elementary books are written fully in the 

 spirit of a sentence which I quote from a re- 

 cent address on chemistry : " Physics, geology, 

 engineering, physiology, botany, zoology and 



