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39C
METALLURGY   OF   CAST   IRON.
losses are often experienced through chill-checks and cracks, the advisability of adopting expanding and contracting *' chills" wherever this may be practicable. Tests Nos. ii, 12, 13 and 14, in Fig. 75, illustrate the expansion and contraction of different sizes of bars poured in pairs from the same iron. These tests show
EXPANSION SIDE. 2               1 1                 1	CONTRACTION SIDE, 123450 i               i               i               i               |               i	7 Inches.
Test No. 9 i    ,   .. ...........	Size of BET l"x l?/'x 4'	(.Fifth JSL1.1C ( Cast 1 s. o.05 (.Sixth j Si. 1.02 jCast 1g. 0.02. (.Seventh j Si. 1.18 Tcast (S. O.OH 7 Inches. ___ i
	Size of Bar l"x l&'ac 4'	
10                   ' 11                     I	Size of Bar ljg"x 2"x 4'	
1"                      j,,. ............ . .......	Size of Bar l"x l&'ae 4'	
13                   I .	Size of Bar 2"x 2^'x 4' ,	
14                        1	Size of Bar l"x l%"x 4?	
2    '       1 i ----------- i             i	128456 ----------------- 1 ------------- --1 ---------------- 1 __________ !__, ________ 1 ________ — J _____	
FIG.    75.—DIAGRAM  FROM  AUTOMATIC RECORDS   OF  EXPANSION  AND
CONTRACTION,   VARIED  BY  CONFINING  EXPANSION  AND
BY   USING BARS  OF  DIFFERENT   SIZES.
that large bars expand so as to increase their interior space more than small ones, thereby calling for the greater *' feeding '' in massive castings. These tests indicate also that light bars contract more than heavy ones, an element not to be overlooked in proportioning casting so as to avoid internal strains so far as practicable, a quality also seen on page 420.
90*.. ~                            I. Sulphur, O.IWW 1»T <TMt,                                                           (	KnurtU Citut