Your cube is black because your volume scatter node is plugged into the surface input of the material output node.
From the manual pagemanual page on the shader,
The Volume Shader output must be plugged into the Volume Input of the Material Output node the Material or World Output node.
Your cube is black because your volume scatter node is plugged into the surface input of the material output node.
From the manual page on the shader,
The Volume Shader output must be plugged into the Volume Input of the Material Output node.
Your cube is black because your volume scatter node is plugged into the surface input of the material output node.
From the manual page on the shader,
The Volume Shader output must be plugged into the Volume Input of the Material or World Output node.
Your cube is black because your volume scatter node is plugged into the surface input of the material output node. Volumetric nodes should be plugged into
From the volume input to render correctly. 
manual page on the shader,
The Volume Shader output must be plugged into the Volume Input of the Material Output node.
Your cube is black because your volume scatter node is plugged into the surface input of the material output node. Volumetric nodes should be plugged into the volume input to render correctly.
Your cube is black because your volume scatter node is plugged into the surface input of the material output node.
From the manual page on the shader,
The Volume Shader output must be plugged into the Volume Input of the Material Output node.
Your cube is black because your volume scatter node is plugged into the surface input of the material output node. Volumetric nodes should be plugged into the volume input to render correctly.
