Times Jumbo 915 Cryptic 44 dn and 47 across

[bergerhenn]

Explanations required please.
44dn - Chemical explosive that's brown stored in gym (7) - looks like should be Heptane but why?
also 47 ac - Column of police holding a line a short time (8) could be Caryatid or Karyatid , again why?
Many thanks.

[bibblebub]

44d HEPTANE [= chemical]

explosive = H.E.
brown = TAN
stored in = put ^ inside of...
gym = P.E.

he pTANe

[bibblebub]

47a CARYATID [=column]

police = C.I.D.
holding = put ^ outside of...
a = A
line = RY [railway]
a = A
short time = T

C a ry a t ID

[ChuckB]

HE & tan (brown) in PE for gym

CID with A RY (railway line) and A T (short for time)