The ESI Act, 1948 was amended first in 1951 even before the scheme was actually implemented first. Chaper V A was, mainly, introduced along with other amendments. The ESI Act (Amendment) Bill No. 24 of 1951 was introduced in Parliament on 19.3.1951. The Amended Act was notified in the Gazette of India Part II Section 2 dated 31.3.1951 in Pages from141 to 144.
Flourishing ESIC 
It is a rare document brought to light for the benefit of new comers and learners who takes interest in ESISheme. Hope to see more such documents.Thanks to the author
P.Gurusamy