diff --git a/src/chemistry/gear/chemistry.h b/src/chemistry/gear/chemistry.h
index db34a9f4d5b71d3dddc235f2bdd0b246e9703aa7..34a0a8e6abbad1e46909c970fe3e6af27b0f415e 100644
--- a/src/chemistry/gear/chemistry.h
+++ b/src/chemistry/gear/chemistry.h
@@ -43,7 +43,6 @@
 __attribute__((always_inline)) INLINE static const char*
 chemistry_get_element_name(enum chemistry_element elem) {
 
-  /* Warning: in the I/O, expect string < 20 */
   static const char* chemistry_element_names[chemistry_element_count] = {
     "Oxygen",  "Magnesium", "Sulfur",  "Iron",
     "Zinc",    "Strontium", "Yttrium", "Barium",
diff --git a/src/chemistry/gear/chemistry_iact.h b/src/chemistry/gear/chemistry_iact.h
index 9e1f6729dcc45231c400a23e25ba1f52c4011542..3e8b913098976f1381377f1711a765023ff9b5eb 100644
--- a/src/chemistry/gear/chemistry_iact.h
+++ b/src/chemistry/gear/chemistry_iact.h
@@ -32,7 +32,15 @@
 #include "chemistry_struct.h"
 
 /**
- * @brief Smooth metalicity
+ * @brief do chemistry computation after the runner_iact_density (symmetric version)
+ *
+ * @param r2 Distance squared between particles
+ * @param dx Distance between particles
+ * @param hi Smoothing length of i
+ * @param hj Smoothing length of j
+ * @param pi #part i
+ * @param pj #part j
+ * @param chem_data Chemistry informations
  */
 __attribute__((always_inline)) INLINE static void runner_iact_chemistry(
 float r2, float *dx, float hi, float hj, struct part *pi, struct part *pj,
@@ -67,7 +75,15 @@ const struct chemistry_data *chem_data) {
 }
 
 /**
- * @brief Non symmetric smooth metalicity
+ * @brief do chemistry computation after the runner_iact_density (non symmetric version)
+ *
+ * @param r2 Distance squared between particles
+ * @param dx Distance between particles
+ * @param hi Smoothing length of i
+ * @param hj Smoothing length of j
+ * @param pi #part i
+ * @param pj #part j
+ * @param chem_data Chemistry informations
  */
 __attribute__((always_inline)) INLINE static void runner_iact_nonsym_chemistry(
 float r2, float *dx, float hi, float hj, struct part *pi, const struct part *pj,
diff --git a/src/chemistry/none/chemistry.h b/src/chemistry/none/chemistry.h
index ec183f7701dd6da0bcea12eff23cad2ee30ab97e..0e787d34918a7de2801ad7d26907726328b651a7 100644
--- a/src/chemistry/none/chemistry.h
+++ b/src/chemistry/none/chemistry.h
@@ -37,6 +37,18 @@
 #include "physical_constants.h"
 #include "units.h"
 
+/**
+ * @brief Return a string containing the name of a given #chemistry_element.
+ */
+__attribute__((always_inline)) INLINE static const char*
+chemistry_get_element_name(enum chemistry_element elem) {
+
+  static const char* chemistry_element_names[chemistry_element_count] = {
+  };
+
+  return chemistry_element_names[elem];
+}
+
 /**
  * @brief Sets the chemistry properties of the (x-)particles to a valid start
  * state.
@@ -75,4 +87,27 @@ static INLINE void chemistry_print_backend(const struct chemistry_data* data) {
   message("Chemistry function is 'No chemistry'.");
 }
 
+/**
+ * @brief Finishes the density calculation.
+ *
+ * @param p The particle to act upon
+ */
+__attribute__((always_inline)) INLINE static void chemistry_end_density(
+    struct part *restrict p, const struct chemistry_data *cd) {}
+
+
+/**
+ * @brief Sets the chemistry properties of the (x-)particles to a valid start
+ * state.
+ *
+ * Nothing to do here.
+ *
+ * @param p Pointer to the particle data.
+ * @param xp Pointer to the extended particle data.
+ * @param data The global chemistry information.
+ */
+__attribute__((always_inline)) INLINE static void chemistry_first_init_part(
+    struct part* restrict p, struct xpart* restrict xp,
+    const struct chemistry_data* data) {}
+
 #endif /* SWIFT_CHEMISTRY_NONE_H */
diff --git a/src/chemistry/none/chemistry_iact.h b/src/chemistry/none/chemistry_iact.h
new file mode 100644
index 0000000000000000000000000000000000000000..24d5bcb78b5defd73a0f7f9f2c3f082a3de79dd1
--- /dev/null
+++ b/src/chemistry/none/chemistry_iact.h
@@ -0,0 +1,64 @@
+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Copyright (c) 2012 Pedro Gonnet (pedro.gonnet@durham.ac.uk)
+ *                    Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+#ifndef SWIFT_NONE_CHEMISTRY_IACT_H
+#define SWIFT_NONE_CHEMISTRY_IACT_H
+
+/**
+ * @file none/chemistry_iact.h
+ * @brief Density computation
+ */
+
+#include "cache.h"
+#include "minmax.h"
+#include "chemistry_struct.h"
+
+/**
+ * @brief do chemistry computation after the runner_iact_density (symmetric version)
+ *
+ * @param r2 Distance squared between particles
+ * @param dx Distance between particles
+ * @param hi Smoothing length of i
+ * @param hj Smoothing length of j
+ * @param pi #part i
+ * @param pj #part j
+ * @param chem_data Chemistry informations
+ */
+__attribute__((always_inline)) INLINE static void runner_iact_chemistry(
+float r2, float *dx, float hi, float hj, struct part *pi, struct part *pj,
+const struct chemistry_data *chem_data) {}
+
+/**
+ * @brief do chemistry computation after the runner_iact_density (non symmetric version)
+ *
+ * @param r2 Distance squared between particles
+ * @param dx Distance between particles
+ * @param hi Smoothing length of i
+ * @param hj Smoothing length of j
+ * @param pi #part i
+ * @param pj #part j
+ * @param chem_data Chemistry informations
+ */
+__attribute__((always_inline)) INLINE static void runner_iact_nonsym_chemistry(
+float r2, float *dx, float hi, float hj, struct part *pi, const struct part *pj,
+const struct chemistry_data *chem_data) {}
+
+
+
+#endif /* SWIFT_NONE_CHEMISTRY_IACT_H */