Nov., r q r j
T I I E J O U R A T A I , OF I.VIIU:STKIAL A N D E Y G I N I I E R I N G C H B M I S T R Y
NSW TYPF. OF P O R T A B L E x.,iaonlxTom nn1:nsr:x.r Fig. I1 show-s the rheostat designed by t h e m i t e r with a yiew t o making repairs morc casy a n d to have a piece of apparatus with sufficient capacity t o fill the needs of most laboratories. It consists of 2 1 coils of nichrome wire giving a total resistance of 3o ohms a n d a maximum capacity of 14 amperes. I t can be
II--A
961
Tlic white casing makes a n attractive looking piece of apparatus. Thc int,erior mume on which the wire is wound is of a special composition which is now being tested out. This same composition used in comhustion boats made t h e remarkable run of j25 steel cornbustinns per boat with t h e test boats still in commission h u t considcrably worse for wear. It is highly
FIG. I1
Hi. 111
used either on t h e furnace shown in Fig. I or with the large one given in Fig. 111. I t holds t h e large furnace in Fig. 111. for a n y length of time at a n y temperature from zoo0 C. up t o Toon0 C. T h e rheostat occupies h u t a few inches of table width and can be set behind t h e other apparatus as illustrated in Fig. I. Repairs are casily made a n d the white board of hard asbestos board gives a cheerful effect. If desircd, twn such rhcostats can be bolted together making a double instrument. The rheos t a t is practically indestructible so long as it8 capacity is not exceeded as there i s nothing about its design to get out of repair. I n Fig. IT, X I is t h e front a n d 13 the back view showing details of construct.ion,
probahle t h a t the muMe will be cqually superior t o t h e old mixture for heating core mutfles. T h e scheme is t o keep these working'mumes already prepared with the heating wire cemented on them ready for usc so that repairs can be quickly made. As t h e furnace cnnsists of three parts its construction it is considerably cheaper t h a n t h a t of t h e old types, besides having the advantages already mentioned. T h e door opens horizontally: t h e author has found this arrangement to he much more desirable t h a n t h e vertically opening door used in some oi t h e old types.
III--- A K E W R E C T A X G U L A K L A B O R A T O R Y EI.ECTR1C
A NEW DIRECT-READING VISCOSIMETER B~ n. F. X~ACMICHIY,.
4Il:FFT.I'
P C R K A C E WIT11 SOl.ID 1IEXT
I,RBOXAT"IY
O B Tllll P A K K W O K l i S
C R I J C ~ B L ESTIITL COITPAPIY OP AWSRICA E'ITIS."XCII
IXSlILATlOh' CASE
m c r i v c a scpiciilhcr 8 . 1 9 1 s
The furnace shown in Pig. I11 is in principle just the samc 3s t h c cylindrical furnace described in Fig. I . A white solid case of kicselguhr surrounds the heating element and working muffle which has a n nvailahlc working space of r i 1 / 2 X j X j in. This is ampic ior most laboratories. To control t h e temperature of t h e furnace t h e rheostat shown in Fig. I1 is used a n d b y means of it any dcsircd temperature can be maintained for hours at a time tip t o ioooo C. T h e author keeps thrce furnaces af this size i n constant servicc. On a c c o u n t of tho simplicity of construction, t h e repairs can h e casily madc and, as no insulating powder is used, t h e furnace is irce from pow
