Sec.4.  How far, in ordinary business, a principal is bound by the acts of an agent, it is not easy to determine.  As a general rule the acts of a general agent; that is, one who either transacts all kinds of business for his employer, or who does all acts connected with a particular business or transaction, or which relate to some particular department of business, bind his principal, so long as he keeps within the general scope of his authority, though he may in some special cases act contrary to his private instructions.  But an agent employed for a particular purpose, if he goes beyond the limits of his power, does not bind his principal.

Sec.5.  An agent is bound, in ordinary cases, to observe the instructions of his principal, even though an act contrary to such instructions should be intended for the benefit of the principal.  The agent must bear, personally, all losses growing out of a non-compliance with his orders; and the profit accruing therefrom goes to the benefit of the principal.  An agent, however, is excused from a strict compliance with his orders, if, after receiving them, some sudden and unforeseen emergency has arisen, in consequence of which such compliance would operate as an injury to the principal, and frustrate his intention.

Sec.6.  When an agent receives no instructions, he must conform to the usage of trade, or to the custom applicable to the particular agency; and any deviation therefrom, unless justified by the necessity of the case, renders him solely liable for any loss or injury resulting from it.

Sec.7.  An agent is bound to exercise ordinary diligence and reasonable skill; and he is responsible only for the want thereof.  Ordinary diligence is that which persons of common prudence use in conducting their own affairs.  Reasonable skill is that usually possessed by persons of common capacity employed in the same business.

Sec.8.  If an agent exceed the limits of his authority, he becomes personally responsible to the person with whom he deals, if the limitations of his authority are unknown to such person.  He is in like mariner responsible, if he makes a contract in his own name; or if he does not disclose the name of the principal, so as to enable the party with whom he deals to have recourse to the principal in case the agent had authority to bind him.  And if the agent even buys in his own name, but for the principal, and without disclosing his name, the principal also is bound, provided the goods come to his use.  Also if the principal is under age, or a lunatic, or otherwise incompetent to contract, the agent is liable.