1.Had he been in his right senses, he could not have thought of such a thing as begging you to give away half your fortune from your own child. "

【难句解析】Had he been in his right senses是个假设从句，相当于If he had been in his right senses；

【句子翻译】那阵子，他十有八九是神志不清了，要不然他就不会异想天开地要你把自己孩子的财产白白送掉一半。

2.that when the money is once parted with, it never can return.

【难句解析】be parted with的意思是“被抛开、分离”；

【难句解析】那钱一旦抛出去，可就再也收不目来了。