Burt and Sally entered into a valid written contract for Burt to buy $1,000$ bottles of $13$

mg$/$ml e$-$liquid from Sally. E$-$liquid was the fluid that fueled electronic cigarettes

$($e$-$cigarettes$).$ The mg$/$ml measurement specified the amount of nicotine in the fluid.

Sally was a supplier of e$-$liquid. Burt operated an e$-$cigarettes store. The contract called

for delivery one month after the contract was signed and payment to be made at

delivery. Two weeks after the contract was signed, Sally delivered to Burt $1,000$ bottles

of e$-$liquid. Burt noticed that $600$ bottles contained $13$ mg$/$ml e$-$liquid, while the

remaining $400$ bottles contained $11$ mg$/$ml e$-$liquid. Burt rejected the $400$ bottles of $11$

mg$/$ml e$-$liquid and accepted the rest.

The following day, the governor of the state in which Burt was located signed a law that

banned the sale and purchase of all e$-$cigarettes, effective immediately. The

development of the law had been covered in the news.

Sally delivered to Burt $400$ bottles of $13$ mg$/$ml e$-$liquid two weeks after the first

delivery. Burt rejected Sally$$s shipment and sought to return the first shipment of $600$

bottles. Burt also refused to pay Sally.

Discuss. Assume that issues of warranties do not apply.