Write a short note on Brownstead – Lowery acid – base theory.

This theory was proposed by Brownstead and lowery.
Brownstead – Lowery Acid :
“It is a substance that is capable of donating a hydrogen (H⁺) ion” (or) 
Proton donor substance is also known as Brownstead – Lowery acid.
Brownstead – Lowery base :
It is a substance that is capable of accepting a proton (${\mathrm{H}}^{\oplus }$) (or)
Proton accepter compounds
Eg : dissolution of NH₃ in H₂O

This theory is also explains conjugate acid base theory.
In the above reaction ‘NH₃’ accept one proton so it act as Brownstead base.
H₂O it looses one proton so it acts as Brownstead lowery acid.