Silkworm

Preparation of formalin solution :
Formalin under saturation is available al40/" while commercial grade formalin contains 36 to 38%
formaldehyde. Formalin dilution to required levels is conducted by adopting any of the two lollowing
procedures :
a) No. of parts of waterto be added for each part of formalin :
Original Concentration of formalin - Required Concentration
Concentration required
Example : To prepare 2% formalin solution where orginal concentration of formalin is 36%
=36-2 = 34 =1:17
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i.e. one part of formalin has to be mixed with 17 parts of water
Thus, lor 1 litre = 1000 = 55.55 ml. of {ormalin + 944.45 ml. of water have to be mixed.
(1 7+1)
b) To prepare desired volume of formalin of required strength:
Concentration of formalin required x Volume required in ml
Original concentration o{ f ormalin
lf the above mentioned example is worked out i.e. one litre of 2o/"lormalin from 36% concentrated
formalin
=2x1000 = 2000 = 55.55 rnl
36 36
To this 55.55 ml. of formalin, water is added to make-up to the desired volume of one litre i.e.,
55.55 ml. of formalin + 944.45 ml. of water or 55 ml formaline and 945 ml. of water
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