il SCIENCE—ADV ERTISEMENTS 
on FOR HEATING BY STEAM 
Produce more water and purer water at a lower cost than any 
other still on the market. 
The distinctive feature of these Stills is that, by a patented 
construction, they utilize the steam generated for heating the feed 
water to the boiling point, so that a minimum of heat is required 
to operate them, and by this preliminary heating of the feed water 
the ammonia and other gases are released and driven off, thus 
producing a water free from all impurities. 
The cost of producing distilled water with these Stills is one- 
fifth to one-quarter of a cent per gallon. As they are self- 
contained and require only the two connections for water and steam, 
they can be installed at very small expense. 
Size 1, capacity 5 gallons perhour .. . $100.00, net 
Size 2, capacity 10 gallons perhour ... 150.00, net 
Size 3, capacity 25 gallons per hour . .. 250.00, net 
Size 4, capacity 60 gallons perhour ... 450.00, net 
Complete descriptive circular upon request, also circular describing 
Stokes Automatic Gas Still with a capacity of 4 
gallon per hour at $18.00, net 
ARTHUR H. THOMAS COMPANY 
IMPORTERS AND DEALERS 
MICROSCOPES, LABORATORY APPARATUS AND CHEMICALS 
1200 WALNUT STREET, PHILADELPHIA 
Note System 
If you ever want to combine good 
work and low costs in an operation 
it is necessary to give time and 
brains to that specialty. 
That is what we have done. As 
| a result we have developed a system 
| of manifolding notes which gives 
perfect legibility of both text and 
| drawings. 
THE KNY-SCHEERER CO. | It is impossible for a single person 
404 West 27th St., NEW YORK | to be a specialist in all lines. Let 
Scientific Apparatus and Instruments, Chemicals, s reli f this one. The re- 
Anatomical and Biological Models, Natural History es yee youn ‘7 . E 2 : i 
Specimens and Preparations, Wall Charts, Museum sult will be a pleasing combination 
and Naturalists’ Supplies. 
GLASS JARS LABORATORY SUPPLIES 
Iliustrated Catalogues on Application 
of workmanship and economy on all 
manifolding you may have. 
Department or 
Tech Typewriting Bureau 
Natural Science | | 39 Trinity Place Boston, Mass. 
G. LAGAI, Ph.D. 
