(c) where he becomes aware of a breach of trust committed or intended by his co- trustee, and either actively conceals it or does not within a reasonable time take proper steps to protect the beneficiary' s interest. Joining in receipt for conformity. Marginal heading. A co- trustee who joins in signing a receipt for trust- property and proves that he has not received the same is not answerable, by reason of such signature only, for loss or misapplication of the property by his co- trustee. Illustration A bequeaths certain property to B and C, and directs them to sell it and invest the proceeds for the benefit of D. B and C accordingly sell the property, and the purchase- money is received by B and retained in his hands. C pays no attention to the matter for two years and then calls on B to make the investment. B is unable to do so, becomes insolvent, and the purchase- money is lost. C may be compelled to make good the amount.