Your photo is a tin type which was first introduced as a format in 1850's in the USA and continued as a relatively cheap form of photo well into the 20th Century.  Usually, the style of clothing will date a photo.  But, unfortunately, with a baby in a long frock which was common for both sexes of babies and the frock styling hardly changed for most of the 19th century it is extremely difficult to date this photo with any accuracy. 

Lesley Edwards
Cheshire, England