500 



CENTEAL SCIENTIFIC CO., CHICAGO, TI. 8. A. 



No. 13756. 



No. 13748. 



No. 13744. 



13730. 



THERMOMETER READING ATTACHMENT, designed especially for use with Calorimeter Ther- 

 mometers. Supported by the thermometer stem, thereby maintaining a constant angle of 

 vision over the whole scale $3.00 



13731. THERMOMETER READING ATTACHMENT, same as No.' 13730, but without support. . 2.00 



1984. THERMOMETER READING ATTACHMENT, consisting of a nickel-plated brass clamp to fasten 



011 the thermometer stem with an adjustable eyepiece 2.00 



13740. THERMO-REGULATOR, Electric, DeKhotinsky Bimetallic, made from invar-brass ribbon. It 

 can be set at any desired temperature from that of the surrounding atmosphere or less, to 

 250 C. or higher ;u necessary. The precision of action of this thermo-regulator is 1 / 4 C. No 

 relay is required in connection with it. Maximum capacity, iy 2 amperes 10.00 



13744. THERMO-REGULATOR, Electric, DeKhotinsky Standard, for precision work in temperature con- 

 trol of water baths, thermostats, etc. It possesses a number of advantages over the usual 

 form. To reduce the lag and to make it respond quickly to changes of temperature it is made 

 of steel, which has about 66 times the thermal conductivity of glass, and is filled with mercury 

 which has about 60 times the conductivity of toluene, which is often used to fill thermo- 

 regulators. Attached to this steel tube is a regulating cap provided with a platinum point, 

 which makes contact with the surface of the mercury in a small glass capillary tube, so that 

 the contact is visible. This capillary is ground to fit exactly the metal parts of the head so 

 that the platinum contact point is exactly centered. When the regulator is to be used in water 

 it must be ordered enclosed in a thin-walled brass tube to prevent rust. The sensitiveness of 

 this thermo-regulator depends solely on tho relation between the diameter of the capillary and 

 the capacity of the steel tube and is almost unlimited. A relay must be used in connection 

 with this thermo-regulator, as the current which passes through the mercury-platinum contact 

 must be kept infinitesimally small. Price dependent upon length and accuracy required. 

 In ordering, specify the capacity of the bath, depth of water, kind of current and accuracy of 

 regulation desired. 



13748. RELAY, DeKhotinsky Iron Clad, for use with No. 13744 for accurate temperature regulation. 

 This must be ordered in connection with No. 13744, and the same information must be fur- 

 nished. When ordered, complete directions will be furnished including a wiring diagram show- 

 ing all connections to be made. Price dependent upon conditions to be met. 



13754. THERMO-REGULATOR, Electric, simple form, consisting of a strip of hard rubber and metal 

 riveted together, the difference in their expansion causing the strip to bend, thus opening or 

 closing an electric circuit through the platinum contact points. Useful as a fire alarm, and in 

 roughly controlling the temperature in hot-houses, incubators and other places where a constant 

 temperature is essential 2.25 



13756. THERMO-REGULATOR, Electric, with condenser, for use in incubators. Will control tempera- 

 tures automatically to % C., through a range from 30 C. to 6C C. Very simple in construc- 

 tion and constant in operation. For full description, see No. 7908 11.00 



